Welcome to the forums.
Bear with me here just recapping a little. When you turn the key on no start if you turn the reverse knob and push down on the shifter does the red light come on? After that you do not touch anything but hold the clutch in and pull up on the shifter you will be in first. If it's stuck in reverse try rocking it and work the shifter up only (it's already down all the way).
Check the reverse cable and make sure the actuator lever by the foot brake is releasing all the way you may have to remove the 8mm bolt holding the reverse cable bracket to check the range of motion? Unless it's had the grey wire mod it will not start and run if it's in reverse (safety feature). Keep us posted. Good luck