I accidentally shorted the +5v terminal with the GND terminal in the AUX-1 section of my RAMPS 1.4 board. I really wish I hadn't done that.
Now Pronterface can't connect to the board and gives this error message:
[ERROR] Could not connect to COM1 at baudrate 250000:
Serial error: could not open port COM1: [Error 5] Access is denied.
I assume I have fried something on the RAMPS board or the Arduino board but I don't know how to figure out which component. The RAMPS board is still somewhat alive: when I press the reset button the green LED flashes twice. Also, the extruder fan still runs fine - it's still getting 5v. And the RAMPS board is still getting 12v power from both of its connections to the PSU.
I suppose it's possible I fried the COM1 port on my PC but I don't know how to check that either.
How do people who know stuff (clearly not me!) isolate problems like this? Thanks!