It's not the hard drive or the power supply...Random power up hang

So I have 2 series 3 tivos. I have fixed both the power supplies and both are on replacement hard drives.

I accidentally did the "Dvr Diagnostics" on one of them yesterday and it hung (I figured out in the past that if you have had both channels tuned with full buffers the DVR diagnostic freezes and you have to unplug to reboot)
Well I didn't want to unplug it so I did some other things while waiting and forgot and it sat on the screen for 24hrs...

Today I unplug it to reboot and it hangs on the "Welcome, Powering Up" screen..

I tried several times to unplug and plug it but nothing.

Kickstart won't work, It reboots instead of running the test.

I take the unit apart and run WD DIagnostics on the drive. Smart passes, and the drive checks out as fine on the scan.

I wondered if it was the power supply so I used the power supply from my other tivo...

Still hangs...

I pop the cable cards out...

Still hangs...

I know from past experience that if the "Welcome, Powering Up" screen lasts more than 5 min you're not going to get a boot and you have to unplug and try again...

Randomly on one of the reboots with the cable cards out it boots. I push the cards in and play a recorded show...All is fine...

I reboot to test and it hangs again...

I am sure it isn't the power supply and the drive test out fine..

I did notice on one of the screen display flashed on and off rapidly and then the "Welcome, Powering Up" screen became more of a magenta and pinkish gold (bad color display of the tivo log) and this flashed a few times and then it hung on this screen...

Double ewe tee Eff?

Thoughts?
Any thoughts on this?