Guys, if you have problems after the update (boot loops, black screens, etc.), please check in recovery mode, if the correct bluez packages are installed.

This update ships and enables bluez5, which caused the above mentioned problems on my Jolla C after the update. One part was updated to version 5, and one part was still on version 4.

After I fixed the installed packages to the correct version in recovery mode, my device booted correctly again.
I forgot to disable openrepos-repositories which may have messed up my update process...