@danj I literally am not talking about the SLI, I made it vey clear I was talking about an external device plugged into the USB port, NOT *any light builtin to the device.
And it's not a weak battery as the battery works fine my friend's macbook air, same model year as mine in fact.
That said, I did finally remember what the 2020 fix was, and it did in fact work: I just needed to remove *all* power for 24 hours. It's working normally now :)