A little update. I checked for continuity between c58 and 59, and it seems fine. I then soldered a patch cable between 59 and 60, gave everything a good clean, as well a good push to all connectors.
With the console dissasembled, I powered it on for a brief time. The game booted normally, with video and sound.
Then, I assembled everything back , powered on the console (with the same game), but it won't boot again.
So I guess, the connector might be causing all the trouble. Couldn't test it though, as my other pal console has a later revision type of the connector that is directly soldered to the board.
I don't think that it might have a bad cpu. I remember running the test cart rom through my sd2snes, but didn't report anything wrong. I'm not 100% sure if it is still ok, since we are dealing with 30 years old electronics.
I'm now trying to source a replacement connector, but I can't seem to source one compatible with my console revision. Living in a European country makes things even tougher, as I don't wont to pay double the price for a 5-6 dollars part on custom duties