Roamio Plus dead after lightning

Looks like my luck's run out, had the Tivo on a UPS but I think the hit may have come in from cable.

Symptoms are that it has no video output (no Welcome screen) - green circle lights up when I plug it in then it gets to the flashing yellow circle for a bit like a normal boot up, then it reboots over and over again. Never outputs anything to the screen.

Stuff I've tried:
component instead of HDMI
swapped out drive
unplugged everything except HDMI and power (including cablecard)

I don't...

Roamio Plus dead after lightning

Roamio Plus dead after lightning