I ended up figuring this out for myself and just wanted to share, since I didn't see much info directly about it on the forums already. My Gemini was hanging at the graphical Linux bootloader screen (with the Planet Computer and penguin logos). It would just sit there for >10 minutes. The back of my Gemini would initially be warm to the touch, but after sitting at this screen for a few minutes, it would be cold, indicating to me that it wasn't actively working on something like an fsck or similar, but had indeed booted partially. I ended up finding out about SSHing via the left USB-C port plugged into my Linux laptop to `gemini@10.15.19.82` which wasn't working for me after a dozen or so Gemini reboots trying with Windows using MobaXterm. It worked the first try on linux, while I had been stuck on the bootloader screen.
Anyway, the problem turned out to be a line that I had put into my /etc/X11/xorg.conf file in an attempt to turn capslock into an additional control key ( I followed the guide at
http://www.noah.org/wiki/CapsLock_Remap_Howto ) . I ended up finding this error after looking through files in /var/log (specifically the line was mentioned as the error in /var/log/Xorg.0.log ).
Hope this helps someone else! I also added my findings to the debugging wiki page at
https://github.com/gemian/gemini-keyboard-a.../wiki/Debugging
