Yes, there is a way to force an upload when you have an existing sketch messing with the pins 0 and 1 that the bootloader uses. It may take a few time to get the timing just right, but here are the steps:
- Remove any wiring that you have connected to pins 0 and 1 on your board.
- Plug the board into your PC.
- Press and hold down the reset switch, this may take more hands then you have but deal with it.
- Start the arduino IDE, select the proper board type, com channel, and load the sketch you want to upload or even
the example blink sketch. - Press upload on the IDE, and only when you see the uploading message in the IDE do you release the reset button.
Again you might have to play with the exact timing needed for this 'well timed manual reset' but it will work if there is no damage on your board.
Let us know how it turns out for you.
Lefty