thanks a lot for your quick reply, much appreciated. The reason for my late answer is this Pixel refusing to accept the job.
Connetced it (Android 10) to USB. Adb and fastboot ready to go and ‘seeing’ the phone.
Installed the vanilla rom 9.0.0 (PQ2A.190205.003, Feb 2019) as advised.
Flashed latest twrp-3.5.0_9-0-sailfish following the recipe - ok, looks good.
Sideloaded /e/ (e-0.13-p-2020120889008-dev-sailfish) following the recipe: abort at 34% (says terminal), device flashing going on forever, finally aborting. Phone remains in a state where it reboots to twrp only.
Restarted the same sideload command after phone reboot into twrp:
Flashing proces on the phone seems to restart at the step it stopped before, at the same time nothing is transferred from PC to phone (adb sideload command aborts quickly).
Assumption: There must be file residues from the first sideload attempt on the phone forcing the aborted flashing to restart over and over. (Wrong idea?)
Tried every wipe method with twrp to get rid of the assumed residues, but no change.
Finally wiped everything, so only twrp remained, at last only the bootloader remained.
Well - same procedure from the start.
Booted to bootloader (only option left),
checked fastboot - fine, seeing the phone,
flashed vanilla stock rom with ‘flash-all’ script, this time a slightly newer 9.0.0 (PQ3A.190801.002, Aug 2019),
-> terminal says, all fine (success),
-> reboot: Google logo appearing, then black screen, buttons not working.
This is called a bricked device, right? Seems to be a zombie, though, the case remains warm, so it’s still busy with something.
This is my fourth Pixel 1, three went smooth to /e/ 9 (from Android 9) an I expected an easy walk this time as well.
Could there be any chance to get the phone on the hook again?
PS: No, I’m not installing Pixels for commercial reasons. One dropped and is hardware damaged (repair shop gave up), second is in use but battery is nearly dead, third is in use but mic failed and needs replacement, going to repair.