pert:
I understand now.Do you see a new port in the Arduino IDE's Tools > Port menu after you plug in the Mega?
If not, make sure you have the USB cable fully inserted into the Mega and the PC.
You may have a damaged/defective or charge-only USB cable. Try a different one.
USB 3 ports can sometimes cause problems. Try a USB 2.0 port or a USB 2.0 hub connected to a USB 3 port.
I got the board changed. Though I am still curious why this happened?
Is 10.3 V too much at the Vin of the Arduino board?? Or I had another issue with my PCB. Actually the common area of the PCB is being shorted with the 5V of Arduino maybe because of some bad solder joint ( I have desoldered and soldered all components back but haven't been able to find the cause). But since all the other components are isolated and have their own supply , I ignored this issue and the circuit was working as desired.
Can this be the cause ?