HP25C repair, help needed

[albertofenini]

Dear All,
while waiting for some spare parts for our third HP-65, we have began the repair project for an HP25C.
This is a old purchase made on TAS, mostly for the collateral that came with the unit, pouch, manuals and battery charger.
The unit was not working, and we would like to give it a try.
It had some light corrosion that we cleaned with lemon juice and rinsed with alcool.
We know that the keyboard has corrosion under the keys but we will deal with that later,
we can see it in transparency, underneath and we will probably dismantle the keyboard
once we will have figured out how to rivet it back together.
We charged a spare battery pack, but the unit looks like dead.
Can anyone one give us in indication of where can we measure voltages and signals to check
what's wrong ? (ROM, RAM, ACT or PSU) ?
Does this board have any test pins ?
Thanks for help !!!!