Only pwr light is on

Last week, one of my NiCd battery packs shorted out and started smoking, so I removed it and put it outside onto the concrete. I then double checked all my wiring, and then continued to work on my robot.

Unfortunately, today I tried using the arduino mega and when I plug in the usb cable, there is no flashing of the rx and tx lights; a quick flash of the light that has "L" next to it and the pwr light turns on.

If I connect a 9v to the VIN and GND pins, the same thing happens.

Is my arduino mega doomed? Is there any way I can save it?

a quick flash of the light that has "L" next to it and the pwr light turns on.

That suggests that the processor itself is running. It could be only the USB bridge is blown. You could try feeding it from another USB to logic TTL interface.

I'm not exactly sure what you are describing. Am I to use the six pins sticking out of the board?

EDIT:

Oh, I see. Use the rx and tx pins in order to send data via USB. Would this work?

Yes that's the sort of think you could use.