Default [Q] HELP! jacked up my phone

i recently rooted and installed safestrap. everything worked fine until i tried to install a custom rom. installation went fine but then the phone just booted to a black screen. i can still access safestrap, odin mode and recovery mode but i cannot restore my backup or install any rom. i am getting an error E:/ unable to mount system. i have been racking my brain and searching everywhere for help and cannot get this figured out. if anyone has any suggestions i would greatly appreciate it.