Nice explanation and batch ...

Here are some additional strings which disable units to read all files from the memory (also SD card) and sometimes help if there are bad sectors in the memory and unit can't enter on USB Mass Storage Mode:

Find and Replace everywhere in the .rgn (boot+fw_main):
30 00 3A 00 2F to 00 00 3A 00 2F
31 00 3A 00 2F to 00 00 3A 00 2F
30 3A 2F to 00 3A 2F
31 3A 2F to 00 3A 2F
2F 47 61 72 6D 6E to 2F 78 61 72 6D 6E

Simple and easy.