I asked about this and was told
It’s worth noting that while our ESCs are rated to 7-26V input, our T200 thrusters are only rated up to 20V, so given you’re using one it seems relevant to stay within that rating regardless of the rating for the Thruster Commander board itself.
The POWER header input requires 7V or more, because it’s regulated down from there to the 5V that the board actually runs on. If you want to provide a direct 5V supply it needs to be via one of the 5V pins on the ESC (OUTPUT) headers.
Because the connections to the ESC(s) are outputted PWM signals, I don’t believe the Thruster Commander can tell whether there are ESCs connected, so I expect this won’t make a difference (SPEED control is supposed to be able to control both left+right together). In saying that, it doesn’t hurt to try if nothing else is working
It may also be worth moving the switch jumper to the OFF position, since that is also expected to output a neutral signal to the ESCs, which should allow them to arm. If that then works to get the remaining two beeps then at least we know the commander microcontroller outputs are working, in which case there may be some issue with the potentiometer or something.
Welcome to the forum @jkwm42
As above, the 3 beeps indicate that the ESC is receiving power and has detected all three phases of a motor, and the green power LED shows that power is plugged in to the thruster commander. The next two (missing) beeps are supposed to indicate 1) valid signal detected, and 2) valid ‘neutral’ (1500us pulse duration) signal received - motor armed and ready for control. If you have access to an oscilloscope you can try measuring the signal on the output pins and seeing if there’s a PWM output or just nothing.
If you’re not getting at least the ‘valid signal’ beep then either something is wrong with your setup (e.g. ESC connected backwards, potentiometer not plugged in, etc) or the thruster commander board is damaged. If you’ve tried the above recommendations and are confident your setup is valid then I’d recommend you email email@example.com and link them to this thread. If it’s determined your commander board is dead on arrival/damaged despite having been used correctly then they’ll be able to set you up with a replacement/refund