All 4 motors were working fine. I plugged into baseflight to do some adjustments, now only one motor will spin.
What adjustments did you make in baseflight? Can you reset the baseflight settings to see if all 4 motors spin again? Did you connect your signal grounds to the ESCs?
Maybe you need to calibrate your ESC’s again, this could be a naive answer, but something like this happened to a friend and the calibration process was the answer.
Hint: The password should be at least twelve characters long. To make it stronger, use upper and lower case letters, numbers, and symbols like ! " ? $ % ^ & ).