I have once put +12V on one of the analog pins (Arduino Uno). Obviously the Arduino did not like it and the 328p chip was fried. Ordered a replacement with bootloader and is working fine since.
Now the reset pin can be something different as the 16u2 or FTDI chip is (to my knowlegde) also is also connected to reset for the auto reset functionality. It is possible that that also got damaged by the overvoltage on the reset pin.
Remove the processor and do the loopbacktest. If it succeeds, get a replacement 328p with bootloder (unless you have an AVR programmer to burn the bootloader yourself). If the loopbacktest fails, the 16u2 or FTDI chip is toast and unless you have got good SMD soldering skills and equipment, you need to get a new Arduino.
I hope you can find a replacement in time for your contest!