Yeah battery was disconnected during the install. Inspecting the screen further, i can see that when using a strong light against it, it actually does display, but the touchscreen/digitizer is not working and without the light against it, nothing shows.
So i installed a trinket m0 in my switch, and initially everything worked as expected. It seemed a bit janky with auto rcm though, so i thought i'd solder the rcm strap as well, since i had not done that to begin with.
I unplugged the flex cables from the two connectors marked in the left side...