troubleshooting Arduino Due board

I'm sure there is a lot of people that have troubleshoot voltage problems on the Arduino Due board. Mine will not turn on using the 12v power supply but is fine using the programming usb port. I tried to trace the voltages from the a/c adapter thinking it goes from there to the 3.3v voltage regulator, I guess not. There is no voltage at the regulator except the negative at pin 1. The other three have no voltage(pin 2, 3 and header on the other side of the regulator. I would assume the voltage goes somewhere else before the regulator. Unable to understand the schematic, can someone direct me where to look? I would greatly appreciate it. I know the boards are not very expensive but I like to repair stuff and why replace the whole board if it might be only a 10 cent item that can be replaced. Thanks for your help. Also there is voltage at the VIN pin.

I have already seen this issue for brand new boards: if the board is powered only via the jack thru a battery pack, nothing works. That’s an evidence that the voltage regulator is out of order, ask a refund to your board reseller.

A thread to understand how voltage regulation should work on that board:

Thanks1 I have heard that too about problems with this board.