It does sound like there's an issue with the connector or (less likely) a rather unfortunate coincidence of failed cables. If you've tried multiple cables, especially when new, and it still fails, it's probably not the cable. Mind you, we did have one user try seven cables, including at least one new one, before finding one that didn't have internal wiring defects.
Anyway, if we can't even talk to to the unit, I'm not sure there's any further troubleshooting we can do from remote. OBsIV is the one who makes decisions regarding RMAs, so I will need to leave the rest to him. I'll flag this post for him to look at again.
OBs?