I'm trying to get my 3D printer running on a RAMPS 1.4 board and it uses an Arduino MEGA.
About a week ago, I uploaded some firmware to the board and I could control 3 stepper motors with my computer. I then must have messed up, because I plugged in the board today and the port it was using before (COM3) wasn't available to be selected.
I accidentally put the board on a metal surface (The top of my computer case) while it was turned on, so I think I might have ruined the board somehow. I also tried to connect an LCD when I had settings for no LCD in the firmware.
Maybe these are beginner mistakes, but yo, I'm a rookie 
In device manager, I could find COM3 greyed out and assigned to Arduino mega. In the properties, it said the device wasn't connected when I could see it was plugged in and powered "ON" with a USB cable.
I tried uninstalling the device and plugging it in again, with no luck.
Restarted my computer. No luck.
The usual sound that occurs when you plug in a USB device doesn't play.
I tried 3 different USB ports on my computer and none of them would get it to recognize.
I used a different USB cable and still no luck.
When I plug in, a yellow LED next to "PWM" blinks then stays on. The green "ON" LED is turned on as well.
I have a multimeter and I tested some voltages between different pins, but it caused the yellow LED to dim so I was worried something was going wrong.