First time after flashing, you just use a current limited power supply. The easiest way to do that is with an automotive light bulb inserted in series with flight battery. I use #1156 or #2056 which are about 2 amp = 25 watt. I have successfully used 0.5 amp bulbs, and I imagine that even 10 amp = 120 watt bulbs would work. It must be an automotive bulb. The Lipo pack must be 3 cell or less.
Red flight battery wire goes to bulb and other bulb connection goes to ESC
Black flight battery wire goes straight to ESC
Try this with working ESCs to understand that it works. When you give a little throttle, the bulb will light up a little. Too much throttle and the ESC will reset (does not hurt it) as if the battery was unplugged.
This only give enough power to allow low power (low RPM) testing.
On low throttle, if you see that the light bulb is bright and that motor does not turn, then it is wrong firmware! Do not test without the bulb in that case! Simply flash correct firmware and test with bulb again. When it works with bulb you can run it without bulb.
If bulb is ever bright and does not go dim when you move throttle to low, it is wrong firmware or could be something else wrong, but if you connect it without the bulb it will burn up.