Yes, I'm getting close!

I reviewed all the steps while creating a new backup image. And I found a major stupidity of mine: I did btrfs restore into a new btrfs img mounted as loop. But I did not create any subvolumes, so the restored data were only directories. There is no visible difference when doing "ls" on the mounted img.

In the end, my new image was bootable after putting the backed up data into subvolumes.

Now there is on thing left: after boot, I get a white screen. While this tells me, it is booting to a kinda workable state, its not yet usable
I chrooted from recovery to unapply patches from patchmanager, as I have read these might be the cause. patchmanager --unapply-all didn't help, still only white screen.

Is there any other way to fix this? I am not on my home network, so the phone is not on the network automatically. Any reinstall has to come from within the phone I guess?

EDIT: on further inspection I found more errors
Seems all the btrfs scrub, btrfs check and btrfs restore didn't catch some stale file handles.
So doing ls -laR from the top is gives me the following stale file handles
@/usr/lib/qt5/qml/Sailfish/Store
@/usr/lib/qt5/qml/Sailfish/Lipstick
@/usr/lib/qt5/qml/Sailfish/Email/libsailfishemailplugin.so
@/usr/lib/qt5/qml/Sailfish/Email/qmldir

well, its not in factory-@ so I try to get those files... stay tuned