Develop Bugs

[Q] Tab Pro 12.2: Screen and Button Issues

I just got this tablet (to replace the garbage SGH-I467) a few days ago (Thu., May 15th). For the first couple of days it worked like a dream. However, the last 4 nights/3 days, I have been encountering some strange issues. What I will do here is describe the issues I've been having, what I have done in attempts to fix them, list some of the things I think may have caused it, and include any additional info/questions.
Before all that though, I would like to mention that I am not a developer, but I am a bit 'tech savvy' and am more familiar with/knowledgeable of technology than the average user. Also, I have spoken with Samsung tech support and even had the support guy access my Tab Pro 12.2 remotely (I will explain what I learned from that below). So, without further ado (I apologize in advance for the long winded nature of this post, but I want detailed):
The Issues:
1) Screen "flickering"—By flickering I mean that it is shutting off and turning on rather rapidly and sporadically, though inconsistently.
I first encountered the problem 3 days ago (the 18th).
Four nights ago (the 17th), before going to bed, I plugged the device into the same outlet I have used for all my mobile devices, when I woke up (on the 18th) the screen was doing exactly what I described. I hit the home button a few times and it stopped.
That night (the 18th) I plugged it back in to the usual spot before going to bed. The next morning (yesterday, the 19th), the screen was "flickering" again. I tried to press the home key a few times, as well as both the soft keys, nothing. In between "flickers" you can see the lock screen, where I have to enter a pin, but even while visible I can't type anything. So this time, to try to solve the problem, I held the power button + volume up to get to recovery and wiped the cache partition, rebooted the device, and viola, it worked again. Thinking that I may have to factory reset the device if the problem persists, I used Kies to backup all my data. I used the tablet the rest of the day, even plugged it in (in a different outlet than the one next to my bed) for a while and had no issues.
Last night (the 19th) I did pretty much the same thing, but this time, thinking that it might be an issue with the device getting too much power (the Quick Start Guide says: "Note: Connecting the travel adapter improperly may cause serious damage to the device."), I used a travel adapter from one of my other, USB 2.0 devices (the only difference between the adapters is the output: 2.0 = 5.0V—2.0A vs. 3.0 = 5.3V—2.0A, and output was specifically what I was concerned with). This morning (the 20th) the problem has returned, but now includes my second issue: the hard home button and both soft keys, back and recent apps, no longer function. So I immediately tried to wipe the cache partition and reboot, but this time it didn't work. Thankfully I had anticipated this yesterday and had that Kies backup, so I wiped the entire device back to factory settings. But alas, it was unsuccessful and the problem persists, including the loss of button functionality, with the exception of the power and volume buttons.
It is important to note that when I first got the Tab Pro 12.2 and set up the lock screen, I used the option that delays the actual locking of the device 10 minutes after screen timeout, but set it so that if I lock the screen with the power button it ISN'T delayed and immediately locks. That being said, a couple of times when the "flickering" stopped long enough to momentarily use the device, I was able to enter my pin and unlock. But when the screen starts flickering again, it locks the device, so the power button must be affected as well. Though since the first factory reset of the device, I haven't set up a pin. I have done several factory resets and none of them have worked. The best result has simply been limited (no back, recent apps or home key) and momentary functionality. I tried using Kies to do emergency firmware recovery, but every time I click the option it disconnects the device.
When Samsung tech support remotely accessed by device (I used one of the momentary functionality windows to download the required application) the agent was able to utilized soft and home key functionality, even though I couldn't. This tells me that it was hardware related, not related to UI/software.
So there are a couple of things I think may have caused/contributed to the problem:
The first, which I vaguely touched on above, is the power issue. Perhaps I have shorted the device out somehow. The outlet I use to charge things while I'm sleeping is on the wall behind my bed, so I have to use a common extension cord, one that has 3 outlets at the end. I have a light plugged into that and in the past have charged both my SGH-I467 (AT&T Note 8.0) and my SGH-I747 (AT&T S4 Active) with that cord and outlet. That is the only place I have charged the SM-T900 overnight, but none of the other power sources I have used have caused these issues.
The second possibility is a virus some sort. I have never used the Samsung app store on any of my other devices, but in order to update the Hancom Office suite I had to. Since I had an enjoyable time using it to that end, I decided to see what else I could find on Samsung's store. I downloaded a couple of things (the "Official Captain America game" and a couple wallpaper/theme apps) and was looking around the store to see if there was anything else I wanted to download. I found several apps that had reviews claiming they were trojans, so I immediately checked the reviews for the apps I had downloaded, but none of them had similar reviews. However, that does not mean they didn't have viruses.
So, what do the resident Android gurus of XDA think about these issues?
I tried searching all over the forums and elsewhere online for people having the same issues, but couldn't find anything. Have any of you ever encountered something similar to this?
Until recently, I hadn't ever heard of anyone getting a virus on an Android device. Are they common? What is the nature of Android viruses?
If these issues do have something to do with overcharging/shorting the device, how can I mitigate that problem? Tonight when I charge the tablet, instead of using the USB 3.0 charging cable, I am going to try just using the 2.0 cable. As I understand it, that can be done by simply plugging it into the right side of the port. Hopefully that will stop exacerbating the problem.
Again, I apologize for such a long winded post. I would like to thank you all in advance. If ever I have problems with an Android, you guys are the ones to ask!
*UPDATE* Before I started typing this I was attempting to run the Kies 'Firmware Upgrade and Initialization', as opposed to 'Emergency Firmware Recovery', to see if that too would disconnect the device. Unfortunately it said that my device needed to be charged first. So I shut it down and plugged it into a surge protected strip and began typing this post. Occasionally I would go over an check the charge. While it was shut down and charging I was able to use the home key to bring up the green battery. Once the charge looked like it was about 75% complete I turned it back on and lo and behold, the "flickering" issue looks resolved and so does the button issue. I can go back, enter the recent apps and task manager, and use the home key functions. For how long this will last, however, is unknown. I guess we'll see in the morning. I'll post what happens tomorrow.

What kind of case are you using? Some users have seen issues with some cases that use magnets for auto-sleep-wake. When the front of the cover is flipped back behind the tablet, the magnets seem to activate the auto-sleep feature
Sent from my SM-P900 using Tapatalk

RE: Case?
dodo99x said:
What kind of case are you using? Some users have seen issues with some cases that use magnets for auto-sleep-wake. When the front of the cover is flipped back behind the tablet, the magnets seem to activate the auto-sleep feature
Sent from my SM-P900 using Tapatalk
Click to expand...
Click to collapse
I am not using a case or cover at all...

same issues here
Sounds exactly as the same issue I have had the last week. I have done several factory resets triad to avoid installing as many applications as I had prior the factory reset (to see If it was an app causing the issue). No solution yet but I will try your way with kies described above. I have a tab pro 8.4.

VeinkWiles said:
So, what do the resident Android gurus of XDA think about these issues?
Click to expand...
Click to collapse
I am no guru, but it sounds like a loose connection. Maybe it is affected by temperature. Try it on a (not too) hot water bottle or on freezer packs.

Mike Austin said:
I am no guru, but it sounds like a loose connection. Maybe it is affected by temperature. Try it on a (not too) hot water bottle or on freezer packs.
Click to expand...
Click to collapse
It's not overheating. It can get warm, but it's never gotten hot. And I've had other devices that have seriously overheated and still functioned, albeit slowly.
**UPDATE**
After I got it working the night I originally posted I let it fully charge (it's important to note that I got it up to about 75% while it was off; green battery the only thing on the screen, and I had home button functionality), then disconnected it and disabled all the radios, put it in power saving and left it over night without power. Doing that I was able to use it all day yesterday. But while I was full-charging it, after it reached 100%, I noticed that it started acting up almost immediately. The sound was on and kept making the lock screen sound (that's how I noticed it from across the room). So it is tied to the power/lock key. But disconnecting it before it could get out of control mitigated the problem. Last night I was going to try to charge it over night with USB 2.0, but I fell asleep before changing the cable out, so it charged on 3.0 all night and is back in poor repair. I'm currently trying to full charge it while off to see if that gives me functionality again.
Either way, each time I fix it the solution becomes more difficult/timely than the previous one. It's clearly not getting better, so I'm going to have to send it in to repairs.
Sent from my SAMSUNG-SGH-I537

VeinkWiles said:
It's not overheating. It can get warm, but it's never gotten hot. And I've had other devices that have seriously overheated and still functioned, albeit slowly.
**UPDATE**
After I got it working the night I originally posted I let it fully charge (it's important to note that I got it up to about 75% while it was off; green battery the only thing on the screen, and I had home button functionality), then disconnected it and disabled all the radios, put it in power saving and left it over night without power. Doing that I was able to use it all day yesterday. But while I was full-charging it, after it reached 100%, I noticed that it started acting up almost immediately. The sound was on and kept making the lock screen sound (that's how I noticed it from across the room). So it is tied to the power/lock key. But disconnecting it before it could get out of control mitigated the problem. Last night I was going to try to charge it over night with USB 2.0, but I fell asleep before changing the cable out, so it charged on 3.0 all night and is back in poor repair. I'm currently trying to full charge it while off to see if that gives me functionality again.
Either way, each time I fix it the solution becomes more difficult/timely than the previous one. It's clearly not getting better, so I'm going to have to send it in to repairs.
Sent from my SAMSUNG-SGH-I537
Click to expand...
Click to collapse
Sorta sounds like a screen grounding problem. I had a nexus seven with this issue and the charger seemed to really make it act up. Needless to say I gave that to my wife and bought this. If the digitizer is not grounded properly it will act up.
Turning on developer settings and set it to show touches on screen. See if when charging the screen registers more touches than you are doing.
Sent from my SM-T320 using Tapatalk

Re: developer settings; display touches
dottat said:
Sorta sounds like a screen grounding problem. I had a nexus seven with this issue and the charger seemed to really make it act up. Needless to say I gave that to my wife and bought this. If the digitizer is not grounded properly it will act up.
Turning on developer settings and set it to show touches on screen. See if when charging the screen registers more touches than you are doing.
Sent from my SM-T320 using Tapatalk
Click to expand...
Click to collapse
Damn! That's an outstanding idea! The only downside is that last night I sent the tablet to Samsung's repair department, so I can't test that out. But once I get it back, if the problem persists I will definitely be doing that first. Thanks for the advice dottat.

Fw:Re: developer settings; display touches
mikegbg said:
Sounds exactly as the same issue I have had the last week. I have done several factory resets triad to avoid installing as many applications as I had prior the factory reset (to see If it was an app causing the issue). No solution yet but I will try your way with kies described above. I have a tab pro 8.4.
Click to expand...
Click to collapse
Hey dude, check out dottat's reply. He's got a really good idea that may shed some light on the source of the problem. Unfortunately, I can't try it out. If you do it, let me know how it goes. Maybe you can take some screenshots? Either way, hopefully you can get something out of it.

[Q] Rooted Motherboard Issues?

Knowing that this is my last resort and with all the wonderful knowledge here on the forums, I'm hoping I might get some creative ideas.
I recently bought a Tab S 8.4, rooted it about 2 weeks after I got it. No problems, everything is working great. Last week, the screen starts to flicker and the tablet reboots randomly. When it does this, the battery goes from 100% down to 12%. Eventually this happens enough where the tablet won't stay on for longer than a minute. Read around the forums and find others mention the exact same issue. Potentially a battery pull/re-plug may alleviate. Tried that to no avail.
I have found that if I hold the battery plug in place *real* tight, by pushing down with my finger, the tablet operates somewhat normally. Could be a motherboard issue.
Anyone run into this at all? Thoughts? Ideas? Replacement parts? I've got a $500 brick on my hands now with no warranty to boot. :crying:
Thanks in advance!

I soldered my battery straight to the board. But before doing that, try spraying some contact cleaner (found in hardware stores) and see if it Will work

hey, i got this issue once ! go to customer service,they will fix it for you in 5min FREE !

sku|| said:
hey, i got this issue once ! go to customer service,they will fix it for you in 5min FREE !
Click to expand...
Click to collapse
Which customer service are you referring to? A local samsung customer service?

Squez said:
Which customer service are you referring to? A local samsung customer service?
Click to expand...
Click to collapse
yes, samsung service center

sku|| said:
yes, samsung service center
Click to expand...
Click to collapse
So they took off the back cover and soldered it back in for you for free with no warranty? I'm a bit surprised they would do that. I'll have to see if I have one in my area.

Please keep us updated
Squez said:
So they took off the back cover and soldered it back in for you for free with no warranty? I'm a bit surprised they would do that. I'll have to see if I have one in my area.
Click to expand...
Click to collapse
Hey Squez please keep us informed and if you get this problem resolved. I am not gonna root my Tab S until I know its safe to do so... thanks and good luck.

TeeShark said:
Hey Squez please keep us informed and if you get this problem resolved. I am not gonna root my Tab S until I know its safe to do so... thanks and good luck.
Click to expand...
Click to collapse
I found a local electronic repair shop that said they could re-solder it for me relatively easily. Brought it in and he said it did look like the terminals on the battery plug had been pulled back a little bit and weren't soldered on there very good (good to hear some type of confirmation on that and he let me view it through a microscope as well). Twenty minutes and twenty dollars later, my tablet is working as it did previously. I've used it sparingly over the last 2 hours, so nothing definitive yet, but the fact that it doesn't restart right away makes me think the issue is resolved.
Thanks everyone for the suggestions!!

Sweet

Squez said:
I found a local electronic repair shop that said they could re-solder it for me relatively easily. Brought it in and he said it did look like the terminals on the battery plug had been pulled back a little bit and weren't soldered on there very good (good to hear some type of confirmation on that and he let me view it through a microscope as well). Twenty minutes and twenty dollars later, my tablet is working as it did previously. I've used it sparingly over the last 2 hours, so nothing definitive yet, but the fact that it doesn't restart right away makes me think the issue is resolved.
Thanks everyone for the suggestions!!
Click to expand...
Click to collapse
eh? 20dorra ??

Squez said:
I found a local electronic repair shop that said they could re-solder it for me relatively easily. Brought it in and he said it did look like the terminals on the battery plug had been pulled back a little bit and weren't soldered on there very good (good to hear some type of confirmation on that and he let me view it through a microscope as well). Twenty minutes and twenty dollars later, my tablet is working as it did previously. I've used it sparingly over the last 2 hours, so nothing definitive yet, but the fact that it doesn't restart right away makes me think the issue is resolved.
Thanks everyone for the suggestions!!
Click to expand...
Click to collapse
Glad to hear you got it working bro.. seems.like a samsung quality or even design issue, they got plenty of space yet decided to use a very small terminal

Battery Results
Just wanted to follow up with everyone that might be experiencing similar issues. After fixing the issue, and de-bloating a bit, my battery life is phenomenal. Much better than when I first got it. I suspect the battery issue was causing some drain as well, even when it wasn't restarting. The attached screen is still with 35% battery left.

Thanks to all those who contributed to this thread. I too was having battery issues. I'd get random restarts, disconnects from the cellular network, forgetting wifi passwords, battery that would go from 50% to dead in three seconds., display glitches etc. I finally opened up my tab which I thought was going to be a pain but was actually pretty easy. By naked eye the solder joints looked fine but under a microscope I could see that all six solder joints on the battery connector were cracked and by pressing on the connector could see the connector move independently from the PCB. Resoldered the joints and everything is good now.

Well my problem is that the battery isn't charging, I get a battery with a red "X" mark when the screen is on but when it is turned off, its charging well but very slow and when it reaches 99% it never goes to 100%. Could it be possible I have the same problem as you guys? no random restarts for me just the issue of sucky battery life (3 hours on wifi) and not charging
Squez said:
Just wanted to follow up with everyone that might be experiencing similar issues. After fixing the issue, and de-bloating a bit, my battery life is phenomenal. Much better than when I first got it. I suspect the battery issue was causing some drain as well, even when it wasn't restarting. The attached screen is still with 35% battery left.
Click to expand...
Click to collapse
Which bloat apps did you exactly remove?

drmodify said:
Well my problem is that the battery isn't charging, I get a battery with a red "X" mark when the screen is on but when it is turned off, its charging well but very slow and when it reaches 99% it never goes to 100%. Could it be possible I have the same problem as you guys? no random restarts for me just the issue of sucky battery life (3 hours on wifi) and not charging
Which bloat apps did you exactly remove?
Click to expand...
Click to collapse
Are you using the stock Samsung charger? Just plug it into the wall and it should be fine. Don't charge from the computer or use a different charger

Got that same problem. My tab will only charge up to 60% under 6 hours. Batterystatus app shows that my 2amp wall charger is just charging at 300mah +/- . Tried my power bank, same issue. Changed the cable and the reading from the wall charger is 1800mAh , could top up the battery in 2hrs

DUHAsianSKILLZ said:
Are you using the stock Samsung charger? Just plug it into the wall and it should be fine. Don't charge from the computer or use a different charger
Click to expand...
Click to collapse
Using wall charger. Never charged via pc...
Any Ideas?

I have experienced this. Flickering of the screen which eventually leads to reboots. Got it fixed at a samsung service center. You rooted it but you're on stock ROM right? I think there's a problem when we root it and stick with the stock ROM. When I rooted my tab again, certain apps started FCing which lead to lags. So I'm gonna wipe this and start from scratch.

Shortened battery life, random reboots, intermittent WiFi ... sound familiar?

I have the SM-T320 (Galaxy Tab Pro 8.4). About 5-6 months ago, I noticed that its battery life began to get much worse (used to last easily through the day, now only lasts a few hours of fairly light use). About two months ago it started suffering from random reboots at odd moments. I had been using one of the CM ROMs and tried others to see if I could solve the problem, with no success. Over the last few weeks the reboots have become so frequent that the tablet is unusable (random reboots every 10-15 minutes) and WiFi has also become unreliable -- the tablet seems to be able to "see" my home network, but can only occasionally get an IP address (even though the signal is strong and other devices have no problem).
Based on the fact that these symptoms have persisted through different ROMs, I strongly suspect it is a hardware issue.
I am wondering if anyone else has experienced these types of symptoms, and if so, how you solved the problem. I don't want to start opening up the tablet unless there is a good chance of success. Is this something a battery re-seat would fix?

Well the second Tab Pro I bought, after trashing the one I received for Christmas. Had a broken Anntena. No clue how that could have happened. As it's a very tiny Board that sits in the lower left Corner that has a Socket on one Side and the missing Gold Finger on the other. The upshot of that was I could only pretty much see the local Net. And Bluetooth had like Zero Range. Replacing that Part with the one from my first Tab Pro I managed to fix that.
As to the Battery, again the consensus here is that it's likely a somewhat lose Battery connection. So I would investigate those Threads for more Details.

Thank you. I did open up the case and re-seat the battery -- and the result was a boot loop, so now I'm not even able to assess the Wifi issues. I will have to spend some more time on it.

Might be a failed battery.
Sent from my SM-G900T

^ That thought crossed my mind as well. The behaviour I'm experiencing at the moment is as follows:
When I plug in the USB charger, I get a boot loop ("battery charging" icon followed by a few lines of text on the screen, followed by a "battery charging" icon, followed by a few lines of text on the screen, etc.) This happens even if I haven't tried to turn the tablet on.
By holding down the power key and the volume-down button I'm able to get to the "install custom ROM" screen but can't continue past it -- pressing any other button only gets me back into the reboot loop.
I found a few tips online that I'll try out later -- otherwise I'll have to decide whether it's worth it to buy a replacement battery (anyone have a good source?)

-The shortened battery life must be due to being used excessively maybe.....It is recommended that you factory reset the device every 6 months so that it doesn't get wasted like that.
-And the reboots is probably because the Memory being used too much as well, once a limit has been reached it reboots so that it doesn't blow up!
-The wifi issue is very common, the SMT320 has a problem connecting to poor connection wifi...make sure your speed is fast enough and is quite close enough to the router. If that doesn't help, try restarting your router, mostly works.
The boot loop is a very annoying thing, make sure you are not dirty flashing and do a clean one,i,e, wipe your system,data and cache and flash a simple and smooth rom....your choice.
Hope this helped in some way....

Amazon... 20.00 prime
Sent from my SM-T320 using XDA Free mobile app

JHW3 said:
Thank you. I did open up the case and re-seat the battery -- and the result was a boot loop, so now I'm not even able to assess the Wifi issues. I will have to spend some more time on it.
Click to expand...
Click to collapse
I have a bit of an update on this, for anyone following along or who finds this thread in the future. Re-seating the battery -- for a third time -- ended up solving the boot loop. The key was that I needed to leave the battery disconnected for an extended period of time (overnight). Things are mostly back to normal now, though the battery life is not what it used to be, so I may buy a replacement.

Tried rolling back to stock?
Had a lot of random reboots with cm, so I tried rolling back to a deodexed, deknoxed, debloated stock ROM.. problem dissapered... Then came back now after I've had the tab for 18 months. But only happens when battery is below 50% and screen light is fixed (turning on auto dimmed the screen a bit but stopped the reboots).
I have a T325.
Cheers!

Random reboots and screen glitching

Hello , nice to meet you all. I am a new XDA user so apologies if i do any mistakes.
Yesterday, i got the 2 GB Ram variant of the LG G3 D855 from a relative. The phone almost works fine, except for two problems:
The first problem is that sometimes, the phone either locks up for about 3 seconds and shuts off (or maybe the screen shuts off? not sure), or either it completely reboots on it's own. I know, there is already information about this on the internet, however, some people say that it's a battery problem, some say it's an overheating problem. I am just confused. By the way, the issue happens no matter if the phone is charging or not. It also happens even when the phone isn't overheating, although it happens less. I may try a battery replacement, but unsure if it will fix it or not.
The second issue is, it's not really a critical issue, but it's just annoying. For some reason, especially when the phone overheats, the screen's right bottom side starts glitching (It also mostly happens on the home screen for some reason). And no, i don't mean flickering. Some glitchy lines appear at that portion of the display for about a millisecond and then goes away most of the time. Today the phone overheated when i was watching YT once and those lines appeared for like 5-10 seconds.
Also, i've noticed that the phone overheats a lot. Like, it gets quite hot sometimes.
I've already tried a factory reset, but it did not fix anything. The phone is running the stock Android Lollipop 5.0 firmware by the way. I did not want to take a risk trying to upgrade the phone to Marshmallow or install a custom ROM because of these problems.
I don't want to spend too much on the repairs of this phone since i've already got an another phone with almost the same specs as the LG G3. But i also want to use this phone. I just like it's design so much. Please tell me if it is worth getting it fixed and what i should do to get it fixed at the lowest cost possible. By the way, i don't understand much about the hardware of smartphones (I will get it repaired to an expert). So please, try to explain the problem as simple as you can do. Thank you and i wish you all a great day.

UPDATE: I've also noticed that the phone also has the screen flickering/disappearing issue.
However, asides from that, i've found an another issue too. So this evening, the phone was overheating too much so i decided to let it cool down a bit. So i closed the apps and put it into sleep mode. After about 5-10 seconds, the phone started doing REALLY LOUD tv static like noises. I immediately pulled the battery out, and i am afraid to turn on the phone because of that. I think the sound didn't come from the battery but i am still afraid.
I will bring the phone to a repair centre. But at this point, i don't know if it is worth getting it repaired. I am so confused. Is the phone dead or not? I've tried pulling the battery out and trying to boot the phne while it was getting charged (DON'T DO IT for your safety) and i get the "No battery" screen. I hope anyone that understands the hardware of this phone will help me. Thank you all.

Slowly increasing hardware problem

Hi all,
I have a general hardware problem with my Samsung Galaxy Tab S4. Maybe someone here has an idea or tip for me.
I still used the factory software without any rooting or unlocking the bootloader. So everything original and up to date.
A few month ago the tablet began to restart in the middle of using it. At the beginning it happened seldom, but then more and more often. Also during the restart new restarts happened more and more often, so that it took several retries, until it started again. Now it is not usable anymore, because it is not running longer than a few seconds before the next restart if it happens to boot completely at all.
I was able to make a factory reset but this didn’t solve the problem.
My first theory is, that this could be a problem with the battery, that it is slowly dying and had more and more problems to hold the voltage. But the problem also exists when the power supply is connected. So I am not sure if this rules out the possibility, that this could be cause by the battery? Does somebody know how this is internally wired, if a broken battery could still have a negative effect when the power supply is connected?
Do you have other ideas/advices, what could be the problem or would could be helpful to do?
Thanks in advance for any help.
Best

The USB power input can't sink enough current to boot it or even run it without the battery acting as a reserve during peak usage spikes.
Replace the battery and go from there.

Thanks, then I will try this.

Vertex9999 said:
Thanks, then I will try this.
Click to expand...
Click to collapse
Hi Vertex, have you tried this already? I have pretty much the same problem and the battery was also my first intuition, but I don't know if buying a new one is worth it. Thanks!

Hi,
unfortunately I didn't had time to do it yet. I want to change the battery myself and for that I will need time and somebody to borrow me a hot air gun, because everything is glued together.
I will report, when I have done it but it will be at least a few weeks.

Alright, so I'll probably try it sooner, I'll update after replacing the battery. Also, if you haven't tried it yet, you might want to try just disconnecting the battery from the motherboard and connecting again after like 20s, I've read that it sometimes resolves this problem, but it didn't work for me. Fortunately removing the back lid of tab s4 is pretty easy, I used hairdryer, so with heatgun it should be even easier.

Thanks for the tips. I am currently on vacation but when I am back I will also try with a hairdryer.
Any additional tips for removing the back lid to somebody doing it the first time beyond what you can see in the youtube videos? How do you glue it back together?

Hi, sorry for the late reply.
I have eventually replaced the battery, and nothing changed unfortunately… I did a factory reset, etc. However I also had an issue that you didn't describe in your original post, which is that USB connection is not working, it only charges the battery, when connected to the PC while booted it's just not visible at all (tried with several cables, two computers, on windows and linux), when in download mode it kind of shows up, but it's not recognized and no drivers or any solution that I've found are working, so I don't know if it's still hardware problem something with the USB related parts or something in the system on lower level. Well, I'll be trying.
About the back lid. Beyond YT videos only thing that comes to my mind is patience. About the glue, you have few options and it depends a bit on how removing the cover goes. 1) glue stays in the more or less same condition as before removing the cover - that's how it went for me - in that case you can just reuse it, just by closing the cover and pressing it down for some time, it's probably not as strong as new but for me it worked just fine, especially if you use a book cover for the tablet there won't be a problem.
But if the glue came off, wrinkled a lot, or just doesn't stick anymore, 2) you can either use a special epoxide glue often with signature like T-7000 or T-800 but if you just look for a glue for smarphones you'll easily find it. Or 3) Buy a special sticker for this exact device which has a specific shape, it's pretty much the same thing as is used by manufacturer.