Not booting after latest update

[Boern]

I tried running

Code:

sudo u-boot-install-sunxi64 /dev/mmcblk2

from a chroot, that just made everything worse and it wouldn't boot at all. But running it from within a fresh mobian-pinephone-20200615.img.gz installation worked.

But now I have the problems with automatic brightness. But I do have ssh-access. Can I somehow do the necessary settings from the command line?
Edit: The screen lit up for about 2 seconds every time I put in a charging cable and so I was able to make the necessary changes.