Hello, I just found a Nintendo Switch Lite who seems all ok:
Many thanks to those who will take time to help me and happy holidays to everyone !
Seems like a failed modchip installation. I would check if the needed points for the modchip have signs of soldering on them. If not, the unit was bad after damaging the SoC, while cutting the shield.
I would try a reflow and hope that the damage on the SoC is not interrupting any circuits.
That’s what I thought when I saw the cut spot on the shield.
Ok, well, I’m going to try my first reflow now 
.
Do you have some recommendations to make this happen as best as possible?
I normaly preheat the board and cover the die of the SoC with capton tape. Apply flux, heat the board with hotair to aprox 210°C and slightly tap the SoC when the solder is liquid.
The SoC doesn’t like heat very much and I try to ceep the time over 200°C as short as possible.
I would check max17050 since usb port been replaced
Jumping straight to an SoC reflow is very bad call IMO and people stand to cause more harm than good, specially if that was never the issue in the first place and now the water is muddied.
Hard to tell based on the fuzzy image but looks like the SoC wafer possibly has damage (if you can provide clearer image here) on edge, and (I haven’t double checked this) but possibly a detached / ajar passive on the left
I’d check resistance to ground on 3V3PDR and 1V8PDR as first basic step given the modchip install and rail relaton (though I’d checking these rails regardless) 
