Ardupilot CubeBlack - Unknown error Message during motortest

Copter: Hexa X
Autopilot: Cube Black
Vehicletype: ArduCopter
Firmware Version: V4.0.3
Board: Kore Carrier Board
Esc’s: T-Motor Flame60 HV (simple PWM Esc’s)

We got this error two messages during motor test:

  1. Error communicating with the autopilot Motor: 5
  2. Error communicating with the autopilot Motor: 6

The motors 5 and 6 also do not spin. Motor 1 - 4 successfully passed the test.
Before this test the copter fly many hours without any problems. We got this copter back because the user performed a hard landing. After the copter shut down motors the copter flipped over.

Back to this error message, we never got before. After checking motors, cables, esc connectors and so on, without finding any fails, the motor test also for motor 5 and 6 successfully passed.

BUT, i do not trust this situation. Maybe we have a problem between main controller and i/o controller inside cube black autopilot.

Any ideas?

If there were any problem, I would guess it is on carrier board rather than the Cube.
The carrier board is longer, thinner and relatively less protected. You may try to replace the carrier board an have a few more tests.