Comment: Re:"Written in JTAG" (Score 1) 757
JTAG is not a language, and I believe blowing eFuses is not a reversible process. This technology is commonly used for chip binning and testing to permanently disable parts of the chip's logic (say, one of 4 cores that didn't pass testing) or features that the client didn't pay for (that one more Mb of L2 cache that costs $50 extra).
Following the description (if it is accurate), it is more likely that if the ROM fails the check a bit is set somewhere in flash or nvram that instructs the bootloader to stop. This memory area is not being written to by stock firmware upgrade sofware used by Motorola, but can be deleted at the service center who have the necessary hardware/software to issue the correct commands.
However it is equally likely that the TFA screwed around with incorrect files, overwrote some part of the Flash he was not supposed to, and simply confounded the bootloader into not working.