Develop Bugs

Flickering screen on boot & no download mode after CM update on D722/LG G3s/jagnm

Hello everyone!
I've been running the nightly CM13 on my D722 for a while now and up until now every update has gone perfectly fine. Today I tried updating to the version of the 23rd of March using the built-in cmupdater but after that my phone has not been booting.
After the LG logo the screen just flickers every now and then and it seems to be stuck on a bootloop. I've tried booting into the recovery mode but this seems to have gone back to the stock LG recovery for some reason. Sadly the stock recovery only gives the option to do a factory reset which seems to be doing nothing as well, it says it's resetting the phone but after that it just returns to the boot with the occasional screen flicker. I've been Googling all over the place to find a solution but the ones that I found all need the download mode which I can't boot into either.
I'm at a bit of a loss, all suggestions to get out of this mess would be appreciated.
In case this is the wrong sub-forum for this thread, pardon me. Please move this thread or tell me where it belongs and I'll get it done.
Thanks in advance,
Alex.

Update
In case it helps, running lsusb on a Linux install returns the following:
Bus 001 Device 011: ID 18d1:d001 Google Inc. Nexus 4 (fastboot)
Kinda sounds like the updater blatantly installed the wrong package given that it's now identified as a Nexus 4...

Mediapad M2 10 A01w

Hi there, I have the above device with unlocked bootloader. It was rooted but I had a problem where the tablet kept rebooting but only after it loaded Android. No amount of following guides fixed it and Recovery and Fastboot were throwing g up problems whenever I tried to flash anything.
Eventually, I managed somehow to switch it on to Chinese update cycle I think and update the ROM with the latest official Chinese EMUI through multiple reboot loops (it downloaded about 10% of the update each time before crashing and getting the next chunk of download next time).
So I'm currently on the latest Chinese ROM running android 5.1.1 and it started working again. However the ROM came without gapps included so I flashed TWRP and installed gapps and I'm back to the reboot cycle. It lasted a long time before restarting again though so I'm guessing it's to do with gapps trying to update.
So I'm back to square one again. Any ideas? Is there any kind of log I can provide to help diagnose? I still have TWRP and have access to that without the bootloop starting again..

How did you rooted it?

Issues with booting

LG G4 815
S/N=511
tl;dr: Bootloop, did a lot of fiddling, finally ended up with installing a "somewhat" working setup in this order (Everything installed via TWRP, TWRP was via fastboot):
1. TWRP (SteadfasterX's) /O version
2. V29a Firmware, keep TWRP
3. Disable big cores kernel (From above V29a firmware thread, first reply by kessaras)
4. LineageOS 15.1
5. Mindthegapps
Having troubles getting it to boot past the LG bootscreen (Once it boots completely, it seems to work fine).
---------------------------------------------------
So yesterday I was browsing my phone when it suddenly restarted. It had done this before multiple times and it always has gotten back to working just fine. Only this time was different, after the LG bootscreen went away, it appeared again. I'm aware of the bootloop issues the device has and was hoping I would get lucky but apparently not.
Configuration when bootloop happened:
-LineageOS14.1
-Stock kernel
-TWRP (3.1.1?, cant remember exact version it was 3+ anyway).
I noticed I could still access TWRP (Although it did crash few times back to LG bootscreen), so I first tried wiping caches etc (No luck). Anyway, I was quite close to just giving up at this point, but decided to fiddle around with the thing. I found out about the issue with one of the "big cores" heating too much and that it was possible to disable those. I decided to give it a try, and while I was at it, wanted to try out the newer LOS15.1. Downloaded titan kernel (no big cores), installed and went onto install LOS. First issue, my TWRP wasn't new enough to install the LOS15.1 (Error code 7). Did some searching and found out about "unofficial TWRP" installations that allowed me to install LOS15.1 (Used SteadfasterX's TWRP, O/ version).
After this I got a few kernel crashes (Green screen with a lot of text, different error codes each time), all searches pointed to my own error during installing stuff (I had older firmware while LOS required newer), and I believe these crashes had nothing to do with the actual bootloop issue. To fix this I went and grabbed the V29a firmware and the big cores disabled kernel which is in the first reply of that v29a thread. After this I managed to install LOS15.1+Mindthegapps (Also rooted it) just fine and it booted up past the LG bootscreen. I grabbed Kernel Auditor to check if the big cores had been disabled and I could only see 4 cores (max 1,44ghz).
Now the phone seems to run fine when I actually get it booted up. I tried restarting the phone and I was stuck in the loop again (Did multiple restarts). I tried booting into recovery (I got into the "factory reset" dialogs just fine which takes you to TWRP) but after that instead of TWRP it went back to the LG bootscreen (Tried again like 3 times). After this I plugged in my phone to my computer and got into TWRP first try(I wonder if there's an actual reason for this, I know it could be just pure luck). Then I went onto the reboot options in TWRP and booted into system. First time I got past the bootscreen but it crashed when asking for my SIM pin code. Second time after booting the same way, I got it working just fine and now the phone seems to be working happily again.
Is there anything I can do myself to trace this issue and improve the chances of booting up the phone or am I forced to just rely on luck and hope it boots completely without crashes (In the case of a crash/I need to restart the phone)?

Stuck on google logo boot screen after twrp recovery & then factory reset

Hi guys, bit of a saga here so bear with me...and also it should be mentioned I have little experience/understanding of tech stuff, so that isn't helpful either lol
I've had a Nexus 5x running 7.1.2 for not quite a week; it came with an unlocked bootloader (strangely). Tried to do the usual install twrp & root as I've done with previous phones (all pre-nougat) but all attempts failed. Couldn't boot into stock recovery from the bootloader at all, it would just boot into the system. OK, next thought was that an OTA upgrade to Oreo might work to restore a recovery - but got the BLOD (naturally lol). I found a fix in a modded 4-core Twrp 3.2.1 -0 fbe img + workaround injector zip from osm0sis & XCnathan32 which by some miracle worked.
So far, so good. Ffwd a few days and google play store keeps crashing on opening; I had the feeling that some glitch happened while it was updating, so I tried all the usual fixes like app cache/data wipes and uninstall updates/renistall google play, delete google account etc which failed. Next I tried a cache & data device wipe through twrp - also unsuccessful. Finally, I thought the only thing left to try would be to restore a backup I made on twrp - this led to the current issue of not booting, stuck on the google logo screen. I even thought what the hell! and attempted a factory reset with twrp - same result, where I am now. Google logo screen, however I still have an unlocked bootloader.
Would anyone be able to suggest where I might go from here? I'm pretty sure the version is N2G48C, if that helps.
Any suggestions very much appreciated...wouldn't mind getting to the 1 week mark with a functioning phone lol

Saga #2
Still no idea what's going on. I realised that I'd backed up and recovered the system and vendor .img files, which according to this thread would be a cause of the issue https://forum.xda-developers.com/nexus-6p/help/stuck-google-logo-twrp-backup-restore-t3320840/page3
So I made another backup without those images, did a full wipe and restored it - still does not boot, still only sitting on the google logo. Tried next to open a cmd terminal to see if I could reflash a stock image, but adb could not connect (maybe because the phone would have been on charging and not file transfer mode?)
Last resort as I saw it was to try the NRT, and see if it would flash stock via the bootloop/softbrick option. Process seemed to be OK, judging by the log - but it did not reboot to the system. Now there is a looping bootloop between the google logo and the unlocked bootloader warning.
Following wugfresh's instructions to factory reset from the recovery (the phone won't turn off via the power button so I just booted straight into the bootloader) Looked for the recovery option, selected....and nothing!!
So there isn't a stock recovery??? How does that work?
And what hope is there for this phone now? (I can't think of anything else )
Anyone have an idea? I've never heard of this before tbh!

Well, my problem has been sorted. In the absence of knowing what the hell I should do lol I managed to get a refund for the phone even though it was a refurb to begin with (something to be said for an honest seller who provides a 3 month warranty!) and I picked up a brand new N5x, which was unboxed on Tuesday. Not even 6 hours into setting it up, the phone started to get progressively hotter and then went into bootloop. Got into the bootloader and tried a factory reset - all seemed OK but halfway through the setup process it bootlooped again. Fortunately it was still within the 2 year warranty, and LG didn't argue about authorising a repair for a phone which didn't get even half a day's use on it lol
Authorised Wednesday, walked into the service centre Thursday and a 1 hour wait later had phone in hand with the PCB/motherboard replaced. Has been working fine (and cool!) ever since. Definitely feel lucky to have hopefully dodged a bullet on this one.
Bonus that they upgraded from 6.0 to 7.2.1 while they were at it; apparently LG considers nougat the "latest" stable version for the 5x.

Question OP 9 Pro stuck on infinite loop using LineageOS

Hi all,
I'm coming back to Android after an absence and would like to run Lineage on a new US unlocked 9P. I followed the directions in the Lineage OS website and unfortunately the phone now is stuck in a constant animation of the blue circle moving left over the arc, and there isn't much I think I will be able to do about it until the battery runs out.
Here's what I did as per the directions:
-got and installed adb and fastboot from the Windows zips from Google
-added the install location to the path enviro variable
-installed the Universal ADB driver from Github
-activated USB debugging and OEM unlocking on the phone
-got the phone repeatedly into fastboot mode but then got stuck since 'fastboot devices' didn't show anything
-got bailed out by another thread here that one needs to check for updates with phone connected and Win will download the relevant USB drivers. Thanks!
-unlocked the bootloader
-downloaded and flashed the 18.1-20210803 recovery img
-sideloaded the copy-partitions 20210323 zip and it got stuck at 47% just like the website said
-did the factory reset
-sideloaded the the LOS 2020210803 zip to the phone and rebooted
When I rebooted it just plays the animation I mentioned at the beginning, so it looks like it's stuck in a permaloop.
I should mentioned that after I flashed recovery and booted into the normal Oxygen mode it would take much longer to boot so perhaps there was something already creating the loop.
I am grateful for any assistance.
Thanks,

How long have you left it? First install of Lineage spins for ages

I think I left it for an hour or so. Thanks for the info - I just turned it on and will let it spin for a while and see what happens.

I let it run until the battery died. I fully recharged it and am letting it run again. Same result of blue circle tracing arc to the left.

Success!
I tried to install the prior version (0720) which was then rejected for being too old. I wiped the storage and then tried 0803 again and it installed. I turned it on, the circle moved for a while and then the Lineage logo came up. I just finished setup, and it looks beautiful.
So far so good!

lexcimer said:
Success!
I tried to install the prior version (0720) which was then rejected for being too old. I wiped the storage and then tried 0803 again and it installed. I turned it on, the circle moved for a while and then the Lineage logo came up. I just finished setup, and it looks beautiful.
So far so good!
Click to expand...
Click to collapse
Everytime you flash a new rom you need to wipe data after

Anytime that happens you just go back into recovery and wipe data a few times and it should work after that.

It would've been due to encryption. Each time you flash a new rom you need to wipe userdata which removes your lock and also removes encryption. If you try to install a rom without doing this first, the rom cannot access that partition, because it doesn't yet know the unlock code/pattern, which is why it just gets stuck trying to do so.

Thank you to the 3 posters above, and I appreciate DJ Sub's explanation, makes sense in hindsight and I'll keep it in mind for the future.
PS - I'm glad to be back to the Android modding community, it's refreshing to be able to steer what OS my phone is running

I had the same problem (also a couple of different boot loop problems) when flashing LineageOS.
I did many things, so can't say for sure which one helped me to fix that, but the things I did were:
Restore from boot loop via MSM tool flashing EU image.
Updating that OxygeneOS to the latest using internal updater.
Repeating the LOS installation process several times in different conditions to isolate the source of the problem. I was changing LineageOS package, OpenGapps package, etc.
One of the problems I've found was that latest OpenGapps package (July 28th if I'm correct) was causing the boot loop on first start (very similar to what you're describing):
Phone tries to boot showing the LOS animation.
It goes for several minutes.
Then the phone vibrates, reboots and it continues from the start.
If I'm not mistaken, it was fixed by using the version from July 24th. The latest package also were removed from the OpenGapps page later AFAIR.
Second problem was after the successful boot. The phone was rebooting from the first setup wizard, booting to recovery (or some other partition) and proposing to make a factory reset.
Not sure which of my steps solved this, but I was updating back to the last LOS package watching closely that I'm flashing the same slot on each step and also making sure that slots are properly copied from one to another with the corresponding script.
Even in the most stable setup I was probably having some setup wizard loop problems, so I was skipping account setup steps and doing that manually later.
I'd say that installing LOS on OnePlus 9 Pro was most difficult and problematic installation in my experience and I did that a lot previously: HTC Wildfire S, THL 5000, Zuk Z1, Xiaomi Mi 5s, Xiaomi Mi 9T (Redmi K20) and several other devices.