[Google Pixel 4a 5G Questions & Answers] Kato0909_:
Hello everyone.

PIxel 4a 5g, bought on launch from Google on Amazon US, no carrier lock, stock ROM, updated to Android 14 by official means, never rooted, USB debugging was on, bootloader locked. I have no prior experience with recovery fastboot etc on this device, but lightly used TWRP and custom ROMs on older phone.

One day I was using my phone, suddenly I saw some glitches on screen and then screen got black. Phone was still on, but no image. I proceeded to do hard reset by holding power button for 10sec. Phone showed the colorful "Google" logo for several seconds, then the top 10px of logo glitched. But the phone booted into OS with no image on screen. I managed to connect BT headphones and even got a few work calls.

Right now the phone itself works, but it's locked with a pattern, fingerprint turned off (phone slightly vibrates, and supposed to show "password required after restart" or something). I can toggle silent mode with power+volume down (it vibrates), I hear notifications, even alarms do work (although with default sound as my custom alarm are encrypted due to phone being locked). But the screen is black, touchscreen does not seems to work either. Alarm still wakes me up sometimes, but to turn if off I must do hard reset(

The interesting part is that screen is not broken, I can manage to go into fastboot(?) mode, and the screen is working there without any glitches. I don't really know is this fastboot mode or no, I get into it by pressing Power+VolumeDown, but its very unreliable. This fastboot(?) screen shows some basic info about phone, bootloader status, with volume buttons I can choose several options: TurnOff/Recovery/Rescue/BarCodes and with power button the selected option activates. The only option that manages to show anything on screen is Barcodes, all the others results in black screen.

I also disassembled the phone to search for any recent water damage, and did not found any. There was some residue of water corrosion on copper foil under screen, but nowhere near any electronics and it looks old... The screen is also fine, and successfully worked in fastboot(?) mode after reassembly.

After reassembly, I once again tried to get into fastboot(?) screen and one time got a succesful boot into OS. The colorful "Google" logo, then boot animation of letter G painted into my launcher colors, then lockscreen with my wallpaper, clock and everything. A second later an alarm on the phone started to ring (although it wasn't the right time, maybe it is meant to go off after boot as "missed alarm" or something) and screen immediately turned black, touchscreen seemingly woudnt work either.

With phone booted I tried to connect via ADB, the device do show up, but "unauthorized". As I remember at this time there is a popup on the phone screen, prompting me to authorize debug connection. With no image an presumably no touchscreen I can do anything. I tried to fastbool list devices wuth phone connected in fastboot(?) mode and didn got any. I am not really expirienced with ADB and Fastboot, I used them once or twice to install TWRP on older phone many years ago and never touched since.

I got several theories:

1. Software. Some graphic subsystem or something in Android, which is not active in basic fastboot(?) mode due to OS not being booted yet. This subsystem or something somehow got glitched, and it turns the screen black after boot. The stock recovery uses the same subsystem or something to show image and manage touchscreen input thats why screen do becomes black, but fastboot(?) does not.

2. Hardware. Even though screen is indeed working, some controller or other IC on the display assembly got some water some long time ago and some pins on it corroded. I could not verify that theory, visually there aren't any visible water damage anywhere near the electronics.

3. Whatever combination of two? Your guess is as good as mine.

I ask you all for some screenshots on Pixel 4a 5G on stock ROM, Android14, to help me try to unlock the phone:

1. Screen after succesfull boot to OS, finger placed on fingerprint sensor, after slight vibration. I am interested in 3x3 dots unlock pattern position and how to get to it if needed.

2. Photo of those Recovery and Recsue options that are accesible in fastboot(?) mode. And if there any good instructions or articles about fastboot/recovery/etc screens on this phone with images that are true to real pixel 4a5g.

3. Screenshot of "control center" in notification shade.

4. Screenshot of "Allow Debud" popup promt on screen.

5. Screenshot of alarm ringing with phone locked before that

Ideally, I want to got the phone running again, at the minimum - to dump files from it.

Did not found this problem on the 4A 5G brach on the forum. Feel free to point out to solution of guide or anything, I am open to learn new things.

I'll be glad to get any help, sorry for the longpost.