HP48G Hardware Troubleshooting Questions/Tips

[Phenixg]

Hello Guys,

I would like to know if any of you have some tips to determine if a processor is dead. My HP48G stopped working a few weeks ago and I tried all the well know tips to revive it but none of them worked for me.
Here are what I have done so far :
* The keyboard foam have been replaced and the connector cleaned with isopropyl alcohol
* Zebra connectors cleaned
* Tried the warm reset, the pinhole reset, the capacitor short and the battery connectors short.
* I left it without battery for 2 weeks.

Here are what I can see:
* There is no sign of life on the display. Nothing when I just connect the batteries, nothing when the "ON" button is pressed and after.
* The "ON" key seems to work: I measured voltage between ground and the ''ON" connector, I get 4.x volts when the on button is pressed; I get 0.0 volt when released. I also measured the resistance, when the on is pressed; the value seems to vary.

Q1: Is there any specific voltage or resistance(or whatever parameter) in some specific spots on the board that would confirm that the processor cannot wake-up or being prevented to wake-up by some other components failure?

Q2: Is there a way to test that display is receiving signals from the processor.

Q3: What are your thoughts?

Thank you Guys.