Hooked up my RUMBA board today. I have 2 problems. First, everything was working but the fan. It wasn't getting any voltage. I went to change some settings in the Marlin firmware, and when I went to upload it, my computer will no longer find the board and I can not select a com port. It worked 30 min ago, but now it won't. I plugged in my Arduino to see if it would find that, and it did. What should I do? I tried the solution on RUMBA wiki and it didn't work. The RX/TX leds never flashed.