Flashed new ROM now phone won't boot up.

I flash Bliss ROM and wasn't getting 4G. Went to go restore my backup and TWRP said it can't because the system was read only. I went to mount option adn took system off read only, restored back up, but my phone wouldn't boot. So I booted back into recovery, flashed Pure Nexus, phone still wouldn't boot up. Tried another ROM, still nothing. Can't get the shome to boot back up.

Now when I go back into TWRP recovery and click on mount, System isn't checked. Did I mess something up? And how to fix?