Hi peoples!!
That's the final update I think. In the final tests I ran, I saw that the 50Amp midi fuse hadn't continuity (open circuit, when tested with the multimeter), so I unmounted and visually inspected it, it was blown.
TURNS OUT A DEAD FUSE CAN END UP IN A RADIATOR EXPLOSION 💥 by shutting off the fan thus overheating the radiator.
And a friendly reminder about starting with a jump starter, beware about electronics, if possible is better to just charge the battery (with an external charger), if possible.

So just changed it and fan worked like a charm, I also checked the voltages and activation with a Launch cps 129 that I have (the last day couldn't read nothing because FCM was not energized)
I also performed a full test, no overheating, no leaking neither overpressuring (though I still have to purchase a new cap; thanks Zip for the tip and the help!!), ran some minutes at 3000rpms with no overheating or warning light whatsoever.
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Here you have a photo if the service manual is not enough. Sorry for the dirt in the motor compartment tho

That's the little m*therfu**er that caused everything. That's the fuse referred in other posts. The black one is the substitute.

Filament clearly broken

So beware folks, at first glance of the obnoxious coolant light, check fuses firstly, that, and the motor fan testing and the A/C triggering the fan are the fastest diagnostic tests you can perform whenever you see the light . That and obviously checking for coolant level.

Ride fast and safe guys!!

Red.
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