LS3 connect and cruise in 68 cutlass has electrical starting issues after 7K miles

[68conv455]

I've had a good experience with my connect and cruise LS3/4L65E but now have some weird electrical issue preventing me from starting the car.
Any suggestions would be appreciated
Here's what happens:
Turn the key to run, speedhut gauges cycle, fuel pump runs, then I turn the key to start, the starter blips for a second and I loose all power to the dash.
gauges go dead, no fuel pump no headlights. Nothing at all when I turn the key a second time.
After waiting (a while), same thing followed by a completely dead car. I feel like there is a fuse somewhere that resets then trips again.
battery is good
Power direct from battery to GM fuse box is good
Power to horn relay is good
I assume there is an issue somewhere between the firewall to ignition switch to the starter
Car has only been pulled into and out of the garage since fall when I work on my other car. No issues till yesterday. I use a battery tender.
Any thoughts?
Thanks.