Belated Update:
My V3 was one of a batch purchased from Grace but never used by the buyer, who then sold them on E-bay. Bought it new in a box. Grace has honored the warranty which is awesome. Got the unit back working good as new of course. Got this from the tech at Grace:
It was a bit of a head-scratcher at first,
but we discovered that the mic amp IC was blown and drawing lots of
current.
When I asked what could cause this:
Hmm... not sure what would cause the mic amp to blow. Do you happen to
plug/unplug mics with the 48V on a lot? That could possibly do it, but
we haven't really tested that theory out.
And No I don't unplug mics hot. BUt anyway, nice to have my V3 back and kicking butt again