You should be able to check if your throttle is working correctly by measuring the voltage on the green throttle signal wire connection on the controller's circuit board.
You can have the black negative probe attached to the battery's - terminal, or simply hold it onto the thick black battery connection's soldered joint on the controller with one hand if you have someone else available to operate the throttle.
You will need to penetrate the protective coating to reach the soldered contacts on the circuit board. If your meter probes do not have nice sharp points, you can simply hold them against a steel needle and use the needle as a probe instead.
The throttles signal voltage on the green wire should vary from 0.8~1V at rest, to between 3.25~4.5V when the throttle is moved to its maximum position.
If the voltage is correct, then the throttle is working correctly and would not need to be replaced.
Just to be safe, I would disconnect the controller from the wheel while carrying out this test.
The voltage on the blue brake signal wire should be ~3V when the brakes are not applied and 0V when the levers are pulled.
If you have a reading of 0V with the brakes disconnected, there could be a fault on the brake signal circuit that would prevent the motor from running, but it could also be a controller fault.
Try unplugging the main harness and measuring the Brake signal voltage again on the circuit board, if it is still reading 0V, then the problem is likely to be the controller
ora short circuit within the controller's wiring harness.
Replacing the Hall sensor in the throttle unit is a fiddly job with a soldering iron, but dismantling the throttle to gain access to it can be difficult on the twist throttles. Early thumb throttles
come apart relatively easily, but I haven't been able to try one of the later thumb throttles, as I don't have one.
It may be worth checking the Hall sensors in the motor to confirm they are still working correctly, as they could also prevent the motor from running. But as you don't see the five flashes with the hall sensors plugged in, they are probably OK.
You can take a look at
this post and
this YouTube video for more details on testing the operation of the hall sensors.
Alan