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I have a pixel 4a running android 11 with a broken screen. The full screen is black; the lower part of the touch screen seems to be responsive but I can't really tell what's going on so I don't know if that is actually doing anything. The networking seems to be broken in some way, I can't locate my phone with 'find my phone' and the nightly backup hasn't run. (mMst stuff is backed up through the various cloud services, but I have a few things that I collect, encrypt and upload to a personal server once a day.) In this case, I was collecting GPS data while planting on my farm and I'd very much like to get that data back.

Things I can do:

  • I still have the password for the encrypted data partition
  • USB seems to work, as I can get the device on fastboot
  • Bootloader is unlocked.
  • I installed the lineage recovery and can start the ADB shell from fastboot using a physical keyboard.
  • I can navigate the early file system but can't see how to decrypt/mount the data partition.
  • I can boot all the way to the lock screen, and I can feel the touch sensor engage when it gets there.
  • I can hear the notification when I plug in the keyboard after boot
  • I can type my password, but I don't know if it is successful

Things I cannot do:

  • I attempted to enable the screen reader by holding both vol buttons; I don't believe I was able to trigger the 'OK' button in the confirmation
  • I attempted to type my password with a keyboard, then connect to a computer, but best case I need a dual port usb dock so I can plug in the computer and keyboard to trigger the accept dialog. I am waiting to go home in a couple days so I can grab a usbc dock
  • TWRP usually has some recovery features but is not available for Pixel 4a/Android 11
  • I doubt I can install a new screen as the frame is quite bent, I might be able to run it without putting it back together but I worry about keeping the rest of the green board intact as there are already some functions (like networking) that have broken. I think pulling out the old screen is likely to be a task that leaves the phone in a worse state.

Things I have not tried:

  • HDMI out to a monitor. From what I've read, it could be possible with a display link style adapter, which I have, but not with me today.
  • Flashing or adding root to my base image. (usually that requires a data wipe.)

It seems the easiest thing to me would be decrypt and mount the data partition and then do a couple adb pulls from the recovery. I'm not quite sure how android 11 does the encryption but I have the password (though the key is probably in the TPM) Is that something that is doable? I didn't see any of the usual suspects when I was looking through the tools in the bin so I'm not quite sure how they are mounting their encrypted partitions.

Izzy
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Pete
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  • The TWRP thread on XDA for Pixel 4A mentions two months ago a beta version for A11 https://forum.xda-developers.com/t/twrp-flame-official.4110641/page-4 I don't know how difficult it is to build TWRP but from my perspective a custom TWRP version that has your password built-in may be a good option (assuming decryption now works). I would try to talk to the TWRP developers about how to make TWRP to some sort of recovery system that just needs to be started and then allows adb access to the decrypted user data as it contains the password. – Robert Jul 20 '21 at 18:11
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    I believe that's what I'm working toward. I see the pixel 4a roms section has a beta version of twrp and I've tried it on my new phone and it seems like it might do what I want. https://forum.xda-developers.com/t/stock-rooted-boot-images-pixel-4a-nov-02.4153249/ – Pete Jul 20 '21 at 18:52
  • While waiting for good advice, our broken-screen tag wiki has a "data recovery" section which might give you some more ideas. There are e.g. tools to mirror the display to your PC so you know what's going on (requires USB debugging active) – or if you cannot do that, make screenshots and retrieve them via MTP to at least get an idea of where-abouts. ADN (with USB debugging) also offers you some leverage on data access and backup. – Izzy Jul 20 '21 at 19:29
  • I have taken a look at it; If I had ADB or MTP I would just copy the files off the phone. – Pete Jul 20 '21 at 19:48
  • you can flash modified ROM with adb enabled, or decrypt from TWRP command line – alecxs Jul 21 '21 at 06:48

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