The board worked before, like a charm, with power from either the USB, the 5V VIN, or even the 3.3V power source. However, in a crash of uploading a sketch, the board froze, and I gave a push to the reset button, the LEDs immediately went off, and won’t come up again by either cutting power or pushing reset button. The board won’t power up by the USB, 5V VIN, and 3.3V source, EXCEPT BY:
Repeatedly scratching the power pins so that electric sparks appear, there is a slim of chance that the power LED comes up and the board boots up and works normally until power cut.
The reset button and the D1(?) diode have been taken out, but it turns out no better and no worse. The board can only be powered up by scratching the power pins and by luck!
Is the board rescueablle? what’s the cause of the failure powering up?
Please help! Thanks in advance!