Atari Portfolio not turning on

[Ren]

Hello everyone!

I've purchased an used Portfolio unit, which it seems to work fine expect for one thing.
Every time I want to switch it on, I have to press one to two times the reset button.
This happens only if the unit has been off for at least a hour or so, otherwise it turns on and off without any problem.
And when this happened, after I turned it on, I see that the set time appears to be behind the current time, which make me think somehow is when the unit totally switched off, without being able to turn it on again normally.

Is this a known issue or does anyone have a possible solution for this?

Thank you in advance,
Renato