My arduino mega2560 won't show up

Hi, I am trying to upload a sketch to my MEGA, but when I plug the board into the computer, it won't show up under the serial port menu. I have tried multiple reinstalls of the IDE, and 9 different computers. Mac Linux Windows7, 10. Is my board toast? My other boards work fine.

If nothing, is it possible to program it with an FTDI cable somehow?

Thanks for any help, –diodes123

When using Windows, do you see a new device appear under the Windows Device Manager device tree after you plug in your Mega to your computer?