If you plug it in via USB, there isnt enough power to move steppers etc, it only provides 5v.
It sounds like you have at least toasted the 5v regulator, first thing is to replace that. (and maybe c5 if its open cct)
Then with 12v applied the led should light...
crossing 12v onto 5v is always bad... It can damage every 5v device on the board.
It sounds like you have at least toasted the 5v regulator, first thing is to replace that. (and maybe c5 if its open cct)
Then with 12v applied the led should light...
crossing 12v onto 5v is always bad... It can damage every 5v device on the board.