[SCCC] Mark V field won't transmit or gets locked

[w6now]

Need some advice on debugging my FT-1000MP Mark V Field (before I send it out to Yaesu or if someone local?).

Symptoms: the rig will go into transmit mode on its own, gets lock and won't come out. 

In order to come out of it, I have to power off the rig, but when I turn it back on it won't transmit with either VOX, CW Key, foot switch/Mic. I have to leave it off for some time, and it seems to be ok after a few hours.

I'm afraid something is getting damaged, so I'll just leave it off for now until I hear back from the gang.

*Some recent changes to the shack include a ground bus including the rig, and I am using a Microham Keyer which I have unplugged completed until I find the problem (this setup used to work without issues until recently).

I appreciate any advice or suggestion including the fix ;-)