How can I fix my Techtrix Bike Max-R, model BMR?

I've not had experience fixing one of your machines, but assuming that the general mechanism is similar to those of other manufacturers, I'd check the following:
Check the wiring that runs from the display unit is not damaged and all the connectors are pushed together properly.
Check the magnet that's attached to the flywheel is lined up with the sensor that sends a signal to the display computer. This needs to be functioning correctly to let the computer know you are pedalling.
The servo that drives the tightening mechanism can fail, but normally this would produce an error message.
Your problem will more than likely be a wiring issue that needs to be traced.

Rupert
December 2019