No Injector Buzz, No Start
I was dealing with roughly the same scenario. Crank, no start, no injector clatter. FICM voltage dropping as soon as key was turned on. Replaced FICM and didn't solve.
It drove me nuts for 2 days trying to diagnose. Jumping the FICM relay brought back injector clatter, but had many weird electrical gremlins. It ended up being the main Power wire feeding into the back of the underhood fuse box. (06 F250)
Couldn't see it from above and even a pain to find from underneath with the fender liner removed.
It had corroded to the point that it was barely making connection, which is weird because all other wiring/battery terminals etc. had no corrosion whatsoever.
Repaired wire (a pain to get to) and truck fired right up!
I found a lot of threads with similar issues, but not many posted what finally fixed the problem. Just another thing to check for



