Hallo, Dr. House
My diagnosis is that, first of all, You should create a backup copy of an internal memory for backup purposes in case of problems.
Place a copy from internal memory on Your SD card. Replace the map with new one. Add cameras to the new map folder on SD. Delete file called "system" from SD card.
Heal the the ttsystem file on SD, heal the map, heal the cameras. Use a tool whatever You want.
Now You should be able to boot to the original TT (with no SD insterted) or insert SD and boot form "healed" system.
Further more, this principle is useful for experimenting with oher (SE) navcores. Safe and sound and always functional. If something goes wrong on SD, be original Just remove the SD.