An unexpected wipe out (AICP style)

My Pixel completely stopped receiving security updates in October 2019.  One year later it's time to move toward a more secure device.  

Last night I decided to see if I could restore my Android 10 Pixel to another Android 10 instance.  The motivation is to capture a point-in-time snapshot of my texts and calls; data which I've found no way to transfer from Android to IOS (the converse however works awesome thanks to the migration tool Google provides in the Pixel).

I had no data of interest on the HTC m8 selected to receive the restore.  I invoked reset all data through the Android 10 UI and it reboot in to Captain Throwback's SAR TWRP (already installed).  I used the defaults for wiping.  When I rebooted, it dived straight into recovery.  I tried adb sideload downloadedbuild.zip, but still went to recovery next boot.  I tried adb push downloadedbuild.zip /sdcard and installing through the TWRP UI, but same result; recovery.

Finally I remembered adb shell and fumbled around with sgdisk to check out if I had a good partition table on mmcblk0.  I did.  cache and data were mounted automatically, but system did not automatically mount.  I went back in to the mount function of TWRP and mounted system.  Back at the shell, it was now mounted at /system_root.  I repeated the adb push downloadedbuild.zip /sdcard and installed it. Upon reboot it booted in to the splash screen instead of recovery.

You might think I was in the clear at this stage, but the entire time writing this, it stayed on the aicp color changing boot screen.

So in closure, the point of this post is that system_root ha to be mounted in order for the aicp 10 zip to successfully apply.  I suspect my issue is that I need to back level to an aicp and 'apply' this 10 zip over the top. We'll see.

See, I did.  I ended up booting back in to TWRP and after several rounds of trying a sideload over of AICP and Lineage 17, I think I finally found the right combo that results in loading instead of faulting back to invoking TWRP.

if already in an Android 10 build, perform a factory reset

in TWRP choose a wipe and format

push over LINEAGE to /sdcard

mount system

install from /sdcard 

optional, test - but it might not complete boot (pwr+vol down for 10 seconds)

if not in TWRP, boot back in to recovery

invoke side-load

mount system

side-load AICP

optional - test, that it works before installing open_gapps, then boot back in to TWRP

side-load over open_gapps-arm-10.0-micro-20200912.zip

that should do it

phone.android.com continued to crash. Setup appeared to restore from backup correctly.