... I used ROM slot 'stock' Maybe I am missing one obvious step - I am not very experienced in flashing custom roms for Android phones and never used safestrap before.
journalctl is your friend You can try to create /etc/ohm/plugins.d/accessories.ini with appropriate values taken from evdev_trace (mce-tools package).
devel-su mount -o remount,rw /system cp kernel /system/etc/kexec/ cp accessories.ini /etc/ohm/plugins.d/