Help with Dead Tivo HD

Hi

I would like some advice on repairing my Lifetime Tivo HD (1.5TB drive upgrade). After a recent power failure, the Tivo would not boot. Symptoms are:

1. No Video on HDMI or composite outputs
2. Hard drive spins up; i can hear the head seeking
3. Fan is on
4. Green and Yellow lights on Ethernet connector light up but do not blink; Et
5. Cable cards removed
6. Only power and video connected (no e-net or cable connection)
7. Power supply voltages OK but a little low; 12V supply was 11.5V

Based on the above, I purchased a replacement power supply from Weaknees.

After power supply was installed, no change in results. Any ideas on next troubleshooting steps?

FYI I am an EE so I can handle complex instrcutions but I only have a DVM.

Thanks