Hi,
I had the a similar problem (black screen)
just download the latest boot.tar.xz
from
http://mirrors.o2switch.fr/batocera/steamdeck/stable/last/
put the microsd card into your windows pc.
drive with the name boot should appear (+ share and games)
If the boot drive does not appear it needs to be repared in the diskmanagment section (windows)
unpack the downloaded boot.tar.xy with 7zip
you get a boot.tar file
unpack boot.tar with 7zip over the files in your drive called boot (replace files)
Finally booting batocera in the steamdeck worked for me without any problems
regards xandl