After installing CM10.1+ Gapps, it booted to a black screen, so I did a hard reset. Went back into TWRP, wiped system, and flashed just CM10.1. After that, it got stuck on the orange Kindle Fire logo (doesn't get to the blue one) and even reflashing the bootloader/recovery doesn't fix it.
EDIT: Tried restoring my system backup from the stock ROM, that didn't work either. Restoring the stock boot image makes it so I can boot into the stock ROM though.
EDIT 2: Must have done something wrong. It's working fine again, but CM10.1 still doesn't work.