A friend gave me his fairphone 2, which didn’t boot anymore. I wanted to try to fix it but I failed.
I tried several OS (/e/, Lineage, Ubuntu Touch and Fairphone OS), but nothing worked.
I tried it with TWRP Recovery, Lineage Recovery, Fairphone Recovery.
ADB / Fastboot worked fine.
Most times it just cancelled after I used “adb sideload” with the error: 1001: failed to update system image.
With Lineage Recovery and Lineage OS (17.1.20210115-FP2-signed) my terminal stopped at 47% and Total xfer: 1.00x, the phone showed the error 1001: failed to update system image.
This manual helped a lot and the installation was completed. but the phone is now stuck in a bootloop. every 30 seconds is starts again.
I tried it with Fairphone Open and there is the same problem.
This manual helped as well, but when I used wipe function in TWRP the phone rebooted when the system was wiped.
Maybe you have some more ideas?