Here is an alert for X7-X7Pro-Nora users with CAN PMU.
If battery voltage drop below 9,5V, easy with a 3S battery, possible with a 4S lazy one, PMU can stop powering Nora or your X7. I had three occurrences with my Nora configuration and I reproduced the drop at home with a Lab power source.
It could be a bad PMU but it is better to check your units and report result (good or bad) to CUAV.
At 10V PMU is powering the Nora, at 9.5V +0-0.5, Nora is not powered and reboot when 10V is restored.