Servo started smoking- now a totally different servo won't work either?

Hey there. I was up past my bedtime shoving wires where they don't belong, and my servo started smoking. When this happened I was hooking it up to an external power supply, and trying to put the ground from the servo to the power supply and the Arduino UNO ground slot on the POWER side (I read you need to do this). I unplugged it immediately, but I think I fried it. :sob: It wouldn't work with the most basic code/setup I've used a bunch of times, even unplugging/closing/resetting everything. Potentially important: The first time I tried after smoke, my computer stopped recognizing my Arduino board when I hooked up the servo (literally as I completed the circuit it did the "duhDuh" noise like you unplug a USB), and after that it gave me a bunch of errors- the first one was saying no COM3 detected. My Tools->Serial Port is greyed out.

I only saw the errors once and didn't get to copy them. Now I just get zero response from the servo.

Here's why I think it's something to do with the board: my other servo I haven't touched all day is behaving the same exact way.

Is it possible I just broke the Arduino board and the servo? All 2 days before I'm supposed to showcase a project?

Please let me know if there's anything I can try. I'm desperate! Sorry for the length, the most common answer to electronics questions is "not enough info"

Some diagnostic steps

Can you connect the Arduino to the PC USB port and is it recognized - does it appear in the Arduino IDE?

Can you upload a simple BLINK program to make the on-board LED blink
Does the IDE say it uploads correctly
Does the LED blink correctly

If these work it suggests the Arduino still has some life in it.

You could then attach a resistor to the leg of an LED (so you can safely plug it into any Arduino pin) and see if you can get it to blink on every pin.

...R

You may have damaged the pot in your servo. Sounds like you are trying to power the servo from the arduino, which can cause issues. You may have also triggered a shutdown of the USB port on the pc due to overload. have you rebooted the pc?