Develop Bugs

GUIDE: What to do in the event of "soft bricking" your tablet...

If you have flashed a rom and your tablet "soft bricks", i.e. it gets stuck at the Samsung splash screen or boot loops Recovery there is an easy way to recover without having to reflash the original firmware in ODIN (assuming you were smart and made a NANDROID backup before flashing your rom).
TURNING THE DARNED THING OFF:
Here's the problem. If you are at the Samsung splash screen or boot looping Recovery, you cannot turn your tablet off by just pressing the power button and you can't pull the battery. This prevents you from getting back into Recovery and restoring your NANDROID backup. So here is what you do:
1) Plug your tablet into your computer (this is important!).
2) Hold down the home, volume down and power buttons until you boot into download mode. Once you are prompted, push the volume up button to enter download mode completely.
3) Now, once in download mode, hold down the power and volume down buttons (not the home button this time) until you screen goes blank (your tablet MUST be plugged into your computer for this to work!). Release the buttons and you will see the battery symbol on your screen. Your tablet is now off - thank god.
4) To enter Recovery mode, hold the home, volume up and power buttons down until Recovery loads.
5) Restore your NANDROID backup.
Disaster averted.

i never manage to enter recovery using the button combination with the 8.4... dont really know why...

edan1979 said:
i never manage to enter recovery using the button combination with the 8.4... dont really know why...
Click to expand...
Click to collapse
Only works if the tablet is off. The key part of this little tutorial is just turning the tablet off when you are stuck in a loop. Once you are off you're golden.

I panicked yesterday because i can't exit download mode with a simple hold of the power key,

LoVeRice said:
I was panicking yesterday because i can't exit download mode with a simple hold of the power key,
Click to expand...
Click to collapse
Hope this helped.

Thanks.

Lots of new roms. Make sure you check those firmware numbers before flashing folks!

When I was stuck on the Samsung logo for 20 minutes after installing this (beta version) rom a week or so back I did this:
1. Held down the Home, Power, Volume up and down buttons for about 10 seconds, not sure if you need all of them held down, but it seems it force restarts the tablet.
2. After the screen went black I immediately held down the Home, Power, and Volume down buttons to enter into download mode.
3. Flashed the latest XAR stock rom from SamMobile.

If anyone is testing a new kernel keep an eye on those temps. An app called CPUTemp has excellent monitoring. You want to be staying under 100c even when benchmarking.

Almost there but
I did everything you said but when i press the recovery combo nothing happens.It is as if there is no recovery!!!
Help plz.I am furstrated and angry!!!

123
mitchellvii said:
Only works if the tablet is off. The key part of this little tutorial is just turning the tablet off when you are stuck in a loop. Once you are off you're golden.
Click to expand...
Click to collapse
Ok that all worked fine, but now that I got it turned off I can't get it to go any further than the charging icon is there a way to push files to it while it off? any help or suggestions are greatly appreciated

Same here. Can get into download mode but can't get into recovery. I've TWRP.
Ok made it into recovery.
Update:
I've now wiped Cache and Dalvik Cache and after rebooting it now says Android is upgrading / Starting apps.
Is this a good or a bad sign?

mitchellvii said:
If you have flashed a rom and your tablet "soft bricks", i.e. it gets stuck at the Samsung splash screen or boot loops Recovery there is an easy way to recover without having to reflash the original firmware in ODIN (assuming you were smart and made a NANDROID backup before flashing your rom).
TURNING THE DARNED THING OFF:
Here's the problem. If you are at the Samsung splash screen or boot looping Recovery, you cannot turn your tablet off by just pressing the power button and you can't pull the battery. This prevents you from getting back into Recovery and restoring your NANDROID backup. So here is what you do:
1) Plug your tablet into your computer (this is important!).
2) Hold down the home, volume down and power buttons until you boot into download mode. Once you are prompted, push the volume up button to enter download mode completely.
3) Now, once in download mode, hold down the power and volume down buttons (not the home button this time) until you screen goes blank (your tablet MUST be plugged into your computer for this to work!). Release the buttons and you will see the battery symbol on your screen. Your tablet is now off - thank god.
4) To enter Recovery mode, hold the home, volume up and power buttons down until Recovery loads.
5) Restore your NANDROID backup.
Disaster averted.
Click to expand...
Click to collapse
my nandroids were not visible... like,wtf,I can't find any of my backups, twrp isn't showing internal or external SDS...weird

Just bricked my Galaxy Tab S. Got it off and it is showing the battery sign. During TWRP I somehow wiped the internal sd. If I download a T800XXU1ANJ6_T800XAR1ANI1_XAR.zip will I be able to ODIN it back to stock? HELP
Lost my backups
Just downloaded and installed via Odin a firmware version of this tablet and all is well. Just have to start all over again, currently writing this due to a Samsung update for the firmware. YEA!

mitchellvii said:
If you have flashed a rom and your tablet "soft bricks", i.e. it gets stuck at the Samsung splash screen or boot loops Recovery there is an easy way to recover without having to reflash the original firmware in ODIN (assuming you were smart and made a NANDROID backup before flashing your rom).
TURNING THE DARNED THING OFF:
Here's the problem. If you are at the Samsung splash screen or boot looping Recovery, you cannot turn your tablet off by just pressing the power button and you can't pull the battery. This prevents you from getting back into Recovery and restoring your NANDROID backup. So here is what you do:
1) Plug your tablet into your computer (this is important!).
2) Hold down the home, volume down and power buttons until you boot into download mode. Once you are prompted, push the volume up button to enter download mode completely.
3) Now, once in download mode, hold down the power and volume down buttons (not the home button this time) until you screen goes blank (your tablet MUST be plugged into your computer for this to work!). Release the buttons and you will see the battery symbol on your screen. Your tablet is now off - thank god.
4) To enter Recovery mode, hold the home, volume up and power buttons down until Recovery loads.
5) Restore your NANDROID backup.
Disaster averted.
Click to expand...
Click to collapse
Just bricked my new Tab S and could not shut it down. I also deleted my sd card during a TWRP move so found the firmware and back to ODIN and I am on my way to recovery, but first thanks is to you to save me from my panic!

Appreciate your advice in getting tab off and back into recovery. Whew!

mitchellvii said:
If you have flashed a rom and your tablet "soft bricks", i.e. it gets stuck at the Samsung splash screen or boot loops Recovery there is an easy way to recover without having to reflash the original firmware in ODIN (assuming you were smart and made a NANDROID backup before flashing your rom).
TURNING THE DARNED THING OFF:
Here's the problem. If you are at the Samsung splash screen or boot looping Recovery, you cannot turn your tablet off by just pressing the power button and you can't pull the battery. This prevents you from getting back into Recovery and restoring your NANDROID backup. So here is what you do:
1) Plug your tablet into your computer (this is important!).
2) Hold down the home, volume down and power buttons until you boot into download mode. Once you are prompted, push the volume up button to enter download mode completely.
3) Now, once in download mode, hold down the power and volume down buttons (not the home button this time) until you screen goes blank (your tablet MUST be plugged into your computer for this to work!). Release the buttons and you will see the battery symbol on your screen. Your tablet is now off - thank god.
4) To enter Recovery mode, hold the home, volume up and power buttons down until Recovery loads.
5) Restore your NANDROID backup.
Disaster averted.
Click to expand...
Click to collapse
Thanks a lot. I just registered at xda developers in order to be able to reply and thank you. You saved my tabS 8.4 two weeks ago. However, I lost this thread since that time and I just found it again today after almost 2 hours of google searching. All that to show my appreciation for helping me to switch off my tablet having been stuck at the booting loop.

I would send you money if I knew how. THANK YOU SO MUCH! I had this problem with a Samsung Tab S I got at Costco, and returned it for a new one. That was about a year ago, and I was sure I would have to take it back again. You are uberawesome!

Kindly help me if u can ^_^
cyaclone said:
Just bricked my Galaxy Tab S. Got it off and it is showing the battery sign. During TWRP I somehow wiped the internal sd. If I download a T800XXU1ANJ6_T800XAR1ANI1_XAR.zip will I be able to ODIN it back to stock? HELP
Lost my backups
Just downloaded and installed via Odin a firmware version of this tablet and all is well. Just have to start all over again, currently writing this due to a Samsung update for the firmware. YEA!
Click to expand...
Click to collapse
Dear,
My case problem is like yours, after I wipe from TWRP I do restart my device & I'm now stuck on Samsung Logo or Battery Logo (if I plug it with my computer).
Now how can I download a new firmware, although I can't open download mode or recovery mode through (Volume Down+Home+Power)?
Thnx n Adv.

Kashkool said:
Dear,
My case problem is like yours, after I wipe from TWRP I do restart my device & I'm now stuck on Samsung Logo or Battery Logo (if I plug it with my computer).
Now how can I download a new firmware, although I can't open download mode or recovery mode through (Volume Down+Home+Power)?
Thnx n Adv.
Click to expand...
Click to collapse
You have a couple of options.
1) Do as the guide says. It usually works.
2) If it didn't work, unplug your device and wait until it discharges the battery and goes off. Then charge it from USB, and turn it on with holding down Home+VolumeDown+Power buttons until DOwnload mode appears. Then press VolumeUp, and flash it from ODIN.

Samsung Galaxy Tab 3 7 Kids T2105 T-2105 can't access recovery mode

I have three (3) Samsung Galaxy Tab Kids T2105 tablets. All are running the latest firmware, T2105UEAOE1.
None of them will boot into recovery. The tabs work, they will boot normally, and then will boot into Download mode. But they will not boot into recovery.
* If I hold down Power+VolUp+Home, or Power+VolUp, continuously, the Tab turns on, and then, about 5 seconds later, turns back off.
* If I hold down Power+VolUp+Home, or Power+VolUp, and release them when the Samsung Logo appears, the device boots normally.
* If I hold down Power+VolUp+Home, or Power+VolUp, and release Power when the Samsung Logo appears, and then continue to hold VolUp and/or Home, the device sits on the Samsung Logo for 20 seconds, then the screen goes blank for a second, then the logo comes back on and sits for 20 seconds, then the screen goes blank... and this cycle repeats until I release the buttons, at which point the device boots normally.
I have done factory resets (through the normal mode settings menus). I have reflashed the latest firmware with Odin3. Nothing seems to fix this problem.
I've been searching the net for hours for this. I see a number of other people who have reported this problem. But nobody has offered a solution. One person stated that he uses "adb reboot recovery" - which is a fine, if ugly, hack - but the fact remains that, for many people, apparently, Stock Android Recovery is not accessible from the Samsung Galaxy Tab Kids T2105.
Does anyone know of an actual solution for this, to restore recovery functionality to this tablet?

Hello,
I have the same tablet, same problem (no stock recovery). None of the button combinations work, and the logo just keeps repeating. My situations is that my 9 yr old daughter locked herself out and can't remember her lock screen password. It's a totally stock tablet (never been rooted or flashed). Because I can't get into the tablet, I'm not sure what firmware version it has, and it does not have USB debugging enabled.
I tried booting into the stock recovery to do a factory reset (since we can't do it in the Settings). I tried flashing the same firmware you mentioned using Odin. It goes through the motions successfully and reboots. But it boots back to the lock screen and its still "locked" (we still see her personal wall paper) - which tells me the flash is not taking. Even though my Odin set up is fine, it does not work (even though everything passed with green lights). I tried going into Safe Mode to try bypassing the lock screen, but even in Safe Mode it still asks for the password. My thinking was to go into Settings and initiate a new password or do a factory reset.
(BTW - the Safe Mode button combination was different for me. Holding Power + Volume Up did not work. Instead I had to hold Power + Volume Up & Down until the logo showed up. Once the logo disapeared, then I had to let go of the Power button only - but continue holding the Volume Up & Down until it fully booted into Safe Mode).
I tried ADB in order to use a password reset/erase command line. But because the USB debugging is not enabled, ADB doesn't see the tablet. There is no other way to enable it via Odin or ADB. And I can't even sideload any Lock Screen Hack apps becuase the table is not rooted, or not USB debugging enabled, or can't get into recovery to flash an .apk or image.
So I am stuck. Why would Samsung block recovery mode??? I have been trying for more than 8 hours. If anyone can help, me and my 9 yr old daughter will greatly appreciate it. My last attempt will be to try Google Device Manager and see if it can somehow unlocks it. Or try Kies (although everything I have read so far says that these have not worked either).
HELPPPPPPPPPP!!!!!!!
ggee

wfire said:
I have three (3) Samsung Galaxy Tab Kids T2105 tablets. All are running the latest firmware, T2105UEAOE1.
Does anyone know of an actual solution for this, to restore recovery functionality to this tablet?
Click to expand...
Click to collapse
Hello,
I'm not sure which one of these did the trick for me, but I was able to get into recovery mode. I'm not sure if your three tables are rooted or not, but I don't think it matters. Try these two methods:
Method #1:
Technically, I think I just stumbled on to this one after successfully completing Method #2 (below). But it's worth trying it first before moving on to Method #2.
-Hold the Home + Volume Up + Power buttons together at the same time (just like the normal process).
-Now, you will probably need to try this next step a couple of time before you get it right. This is because it happens pretty fast and you need to time it perfectly.
-Notice that when the screen turns on, the actual first thing that happens is that the the screen backlight turns on and glows first. This happens first and a split second later the first Samsung logo flashes.
-You need to let go of all three buttons at the same time as soon as you see the backlight turn on, but before the Samsung logo flashes.
This is the sweet spot, and it happens pretty fast. But once you do it at the right time, the tablet will go black again and then the recovey mode will show up. It works for me every time.
Method #2:
I thought somehow the recovey mode portion of the firmware had become corrupter somehow. So I decided to flash a custom recovery using Odin (since at that time I hadn't stumbled onto Method #1 yet). Make sure to use gr8nole's custom recovery version for the SM-T210 and SM-T210R (these are the equivalent wifi versions of our Kids tablet). His versions have fixed some known bugs that CWM/TWRP have with the wifi version of our tablets. Make sure to download and flash the CWM or TWRP .tar file for Odin (I personally have always liked CWM over TWRP).
Here is his link: http://gr8nole.blogspot.com/
Also mentioned here: http://forum.xda-developers.com/showthread.php?t=2437219
-Make sure you have all the correct USB drivers for the tablet installed on your computer.
-Open Odin and load the .tar file that you downloaded from gr8nole into the PDA or AP slot (depending on your Odin version).
-Let Odin check the m5d verification for successful authorization.
-Once Odin is ready, then boot the tablet into Download Mode (Home + Volume Down + Power button)
-Connect the table to a USB cable that is attached to your computer's main USB port.
-Odin should now recognize that the table it connected to a valid COM port.
-Click <Start> button on Odin and it should flash the costum recovey .tar file pretty quickly.
-The tablet will simultaneously flash a progress bar and start to automatically reboot (also pretty quickly).
-Disconnect the tablet from the USB cable now.
If the tablet does not automatically reboot to the new custom recovery screen, then just power off the tablet completely. Wait 30 seconds, and then boot the table to recovery mode use the Method #1 shown above. You should now be able to go into the new custom recovery mode you flashed with Odin (CMW or TWRP). It should all work now.
From this point you can download and install SuperSU to add root (if you want to).
Let me know if this works for you.
ggee

Using Download Mode Without Display

I've got a Samsung Galaxy Tab S 8.4" which no longer has a working display. I want to back up as much of it as I can, so I've set to work on installing TWRP. I already installed and used it successfully on an identical device (but with the screen working!), but this time round, it just doesn't work.
TL;DR: My questions: Is there any way to add TWRP to my device without using Download Mode? Is there any way to check if TWRP is installed? And is there any way to, once I'm in Download Mode, determine that without exiting and without a display?
My process: I've tried getting into Download Mode both by shutting down, then holding the power, volume down, and home buttons for ten or so seconds, then following up with a volume up press to confirm that I want to use download mode; and by just typing reboot download in adb. I've then used Odin to flash it with TWRP. Odin shows a PASS, so I wait for the tablet to reboot into the normal mode.
Once there, I've tried to get into TWRP by both shutting down, then holding the power, volume up, and home buttons for ten or so seconds; and by just typing reboot recovery in adb. But, no matter how long I wait, my device never reconnects to my computer, and adb shell can't connect to it.
When I've rebooted into recovery, I seem to be able to press the power button once, and it reboots into the normal boot mode; this indicates to me that it's in the normal Recovery Mode, since this isn't default TWRP behaviour. That would mean that TWRP hasn't been successfully installed.
I came across this thread, which suggested that using Odin to flash a device while it's not in Download Mode would likely have no effect. My figuring, then, is that I haven't successfully booted into Download Mode ever.
Interestingly, when I ran Odin during what I thought was Download Mode, it did seem to restart the device when it was done (at least, after a bit I could connect to it normally with adb).
My question, then: Is there any way to add TWRP to my device without using Download Mode? Is there any way to check if TWRP is installed? And is there any way to, once I'm in Download Mode, determine that without exiting and without a display?
I know it's a bit of a tricky one, so :good: if you can think of an answer to any of those.

I wonder if the hdmi adaptors would work in recover, they are quite cheap to buy.

Your issue is likely that you're not manually booting to recovery IMMEDIATELY after flashing with Odin. TWRP is obviously successfully flashing.
You need to disable auto-reboot then when odin states PASS, force manual reboot by holding POWER + HOME + VOL DOWN for a few seconds then change to VOL UP whilst still holding the other buttons.
This is all gonna come down to timing, so you may have to do it several times until you get it.
In any case if all you need to back up is your stuff stored on internal storage, you don't need twrp for that. Just connect the tablet to the PC and use MTP to backup what you need.

Note is stuck in a bootloop - and I can't seem to install recovery/not sure if it's corrupt

Hey all,
Hope you've been keeping safe and well.
So I was flashing the new PixelExperience ROM - and seems like I made an error somewhere along the way.
I'm looking to return to stock, and then give the process another shot - but at the moment my phone is stuck in a bootloop.
The bootloader is unlocked - and the boot goes through the following screens before rebooting:
1. Samsung Logo
2. "The phone's bootloader in unlocked....Press power key to continue"
3. Samsung Note 10+ Logo Screen.
I'm trying my best to try and boot into either download or recovery mode, but to no avail - it just restarts the bootloop on each combination I've tried.
Any solutions on how to get moving with this?
Thanks!

rajalot said:
Hey all,
Hope you've been keeping safe and well.
So I was flashing the new PixelExperience ROM - and seems like I made an error somewhere along the way.
I'm looking to return to stock, and then give the process another shot - but at the moment my phone is stuck in a bootloop.
The bootloader is unlocked - and the boot goes through the following screens before rebooting:
1. Samsung Logo
2. "The phone's bootloader in unlocked....Press power key to continue"
3. Samsung Note 10+ Logo Screen.
I'm trying my best to try and boot into either download or recovery mode, but to no avail - it just restarts the bootloop on each combination I've tried.
Any solutions on how to get moving with this?
Thanks!
Click to expand...
Click to collapse
Timing will be the key. To help out, boot up as you have been, but as early into the boot cycle press and hold the Vol - and power button for up to 5 seconds (until phone manually shuts off) [it will actually reboot the phone])), then the instant it powers off and begins to power back on (try a few times to get used to the timing) press and hold the key combination for recovery or download mode. In my experience whatever combination you go with while booting, the power button only needs to be held for the first 5 seconds or so of the combo button press/hold.
The other button, Vol+ or Vol- should constantly be held until desired mode begins to load.

louforgiveno said:
Timing will be the key. To help out, boot up as you have been, but as early into the boot cycle press and hold the Vol - and power button for up to 5 seconds (until phone manually shuts off) [it will actually reboot the phone])), then the instant it powers off and begins to power back on (try a few times to get used to the timing) press and hold the key combination for recovery or download mode. In my experience whatever combination you go with while booting, the power button only needs to be held for the first 5 seconds or so of the combo button press/hold.
The other button, Vol+ or Vol- should constantly be held until desired mode begins to load.
Click to expand...
Click to collapse
Thanks for your quick and detailed reply man, appreciate it.
Still trying, new cords, ports, the whole buffet. Will keep at it.
Major flag though - my PC doesn't recognise the phone anymore, checked the USB ports in Device Management and nothing comes up. I've tried different cords and ports to no avail.
I have a feeling that because the device doesn't think it's not plugged in - it doesn't boot into recovery.
Just another detail - the flash goes on just before the reboot. Does this signify anything?

rajalot said:
Thanks for your quick and detailed reply man, appreciate it.
Still trying, new cords, ports, the whole buffet. Will keep at it.
Major flag though - my PC doesn't recognise the phone anymore, checked the USB ports in Device Management and nothing comes up. I've tried different cords and ports to no avail.
I have a feeling that because the device doesn't think it's not plugged in - it doesn't boot into recovery.
Just another detail - the flash goes on just before the reboot. Does this signify anything?
Click to expand...
Click to collapse
I'm not familiar with any significance the flash may point to. You've probably already done this.....but be sure to reboot PC....
Have you tried booting to recovery yet?

How to reliably start TWRP

I have TWRP installed, and have managed to run it a few times. Now I cannot start TWRP at all.
From off, if I switch on, the following happens:
1) Screen with Samsung Galaxy A70 - Secured by Knox
2) 0.5 seconds later another screen, "this phone's bootloader is unlocked and it software integrity. .." and "press power key to continue..."
3) 5 seconds later, same screen as (1)
4) 3 seconds later, red letters "this phone is not running Samsung's official software"
5) 3 seconds later blank screen with "samsung" and then booting to android.

In my experience I have to flash twrp every time I want to use it( I don't know the reason but I couldn't fix it ) , for booting twrp on the other hand I turn off the phone first, then I press power button+volume down until the "this phones bootloader..." screen appears, here is the tricky part, you have to quickly let go of these two buttons, press power button, let go of the power button (after the warning disappeared) and then press volume down button (and hold it) until twrp logo appears, this happens really fast so you may need to do it a few times to get used to it.

mobin22 said:
In my experience I have to flash twrp every time I want to use it( I don't know the reason but I couldn't fix it )
Click to expand...
Click to collapse
Yes, same here, the only time I have managed to run TWRP on this phone, is right after a flash.
mobin22 said:
and then press power down button
Click to expand...
Click to collapse
Do you mean volume down?

Zilliman said:
Yes, same here, the only time I have managed to run TWRP on this phone, is right after a flash.
Do you mean volume down?
Click to expand...
Click to collapse
Power off the device, plug into a pc, wait for it to start charge, hold vol up and power till it turns on. Wala boots to twrp. If you have magisk installed,you can use the reboot option within magisk.

mobin22 said:
In my experience I have to flash twrp every time I want to use it( I don't know the reason but I couldn't fix it ) , for booting twrp on the other hand I turn off the phone first, then I press power button+volume down until the "this phones bootloader..." screen appears, here is the tricky part, you have to quickly let go of these two buttons, press power button, let go of the power button (after the warning disappeared) and then press volume down button (and hold it) until twrp logo appears, this happens really fast so you may need to do it a few times to get used to it.
Click to expand...
Click to collapse
Samsung changed how to enter recovery on Android 11. Power off device, plug into pc, wait for it to charge, then hold vol up and power till it turns on. Alternatively, if you have magisk installed, use the reboot options within magisk.

I did that. Thanks!
But it has gone to:
Android Recovery
Samsung /a70qxx/a70q
11/RP1A.200720.012./A705FNXXUB5DVB3
user/release-keys
Use volume up/down and power.
Reboot system now
Reboot to bootloader
Apply update from ADB
Apply update from SD card
Wipe date/factory reset
...
...
...
Where is TWRP? It seems it's gone.

Zilliman said:
I did that. Thanks!
But it has gone to:
Android Recovery
Samsung /a70qxx/a70q
11/RP1A.200720.012./A705FNXXUB5DVB3
user/release-keys
Use volume up/down and power.
Reboot system now
Reboot to bootloader
Apply update from ADB
Apply update from SD card
Wipe date/factory reset
...
...
...
Where is TWRP? It seems it's gone.
Click to expand...
Click to collapse
That's because you're not installing it properly go back to my guide and follow it exactly and stop listening to these other people. I've been modding this device since it first came out with Android 9, I know every inch of this device. You're getting confused by what other people are telling you

MarvinMod said:
5- Press and hold vol down and power till the screen turns blank then immediately press and hold vol up. The device will reboot then land you in the twrp splash screen
Click to expand...
Click to collapse
It fails here, on this step. After successful flash of recovery.tar, power + vol down to reboot, cable still connected, nothing you can do now can bring TWRP up. The phone boots into Android.
EDIT: I think I have now got it. I will update in a few mins.

Zilliman said:
It fails here, on this step. After successful flash of recovery.tar, power + vol down to reboot, cable still connected, nothing you can do now can bring TWRP up. The phone boots into Android.
EDIT: I think I have now got it. I will update in a few mins.
Click to expand...
Click to collapse
After successful flash of recovery.tar, power and vol down to reboot, as soon as the phone screen goes blank, immediately release all keys and press and hold vol up. Must be as soon as screen goes blank. The device will then reboot twice and land you in twrp splash screen. You must hit vol down and power after successful flash then when screen blanks, vol up. If you miss this step, twrp will not hold and revert back to stock recovery.

Here is the notes I made today:
****************************************************************
INSTALL + START TWRP
phone is off
press up + dn
insert cable
go into download (press up)
ODIN 3.14 + AP:tar(vbmeta.img+twrp.img), auto reboot off, press upload
when it succeeds, press dn + pwr until it reboots
then quickly up + pwr until it starts (no need to hold down)
this starts in TWRP
from powered off
press pwr button
goes into twrp or android(system) -- depending on what was used last time
if we used reboot->system last time it will now **Always** go into system!
to go back into twrp:
switch off
power cable until charge
pwr + up until it starts
****************************************************************
The above means that you CANNOT go back to TWRP unless you have a cable and a PC near by.