" I don't see where there would be enough room inside the ONE for the wire to just "Fall Off"! "
Well it actually can. Not fall off literally but rather disconnect from its socket. This has actually been an issue with the HTC OneX's wifi antenna also.. If u check out this guide: http://www.slashgear.com/htc-one-tea...rity-28275687/
you will see the black cable that goes from top to bottom and connects two pcbs. That's your culprit if indeed you have a hardware issue. What i would do if i were you is first find one of my carrier's antennae and go as close to it as possible and see if you get any reception at all (best chance i guess is in a subway station). I guess that once you're that close to a transmitter your circuitboard is sufficient antenna though i might be wrong. If i am right and you get reception than its hardware. If you dont get reception than the cause is uncertain..can be hardware, can be software.. Anyway, i wish you best of luck with fixing your problem!
Device: HTC ONE [M7]
History: Bosch COM509, Ericsson T20e, Sony Ericsson T310, Sony Ericsson T610, Nokia 6600, Nokia 6630, Nokia 7710, Nokia N72, Nokia N95, Nokia N97mini, HTC Desire S, HTC One S