I just did a quick search and found where I did a write up some time ago on
how to get the radio back. Seeing you are doing a revision of the warnings of what NOT to do (etc), I figured you might wish to scan that thread and see what went wrong for some people. It seemed likely that you have already seen recent threads dealing with it, but as I made this post over a year ago perhaps it may have went unnoticed.
Some findings that might be worthy of mention- power fluctuations during radio install kills it, and sometimes apparently even prl updates kill it.
Also, I've heard of major quality differences of exact type phones giving very different results with the only known difference being location of manufacturer...Japan vs China...etc. I haven't researched if that's applicable here. Merely brainstorming possibilities...
Just didn't want these paths to go unconsidered.