Some people may meet this problem,If this error causes the pixhawk to fail to arm, it is because the voltage value cannot be read from the 3DR power Module.This problem is not caused by the low voltage of pixhawk hardware, but because pixhawk cannot read the battery voltage.
the following issues cause this problem
1.No using 3DR power Module .
2. The 3DR Power Module is bad, can not read the batter volate from 3DR power Module.Or can not support 5.2V-5.3V voltage.
PX4 firmware should use 3DR Power Module, what is Power Module?
This is 3DR power Module.
How to judge whether the 3DR power module is normal?
if your 3DR power Module does not have 5.2V-5.3V, it means that your 3DR power Module is bad. Can not use for PX4 firmware.
If you add 3DR power Module and it is GOOD ,how to calibrate it?
More information you can see here, https://docs.px4.io/v1.9.0/en/config/battery.html
Make sure the BAT_SOURCE is Power Module.
If you can not calibrate the batter data,it means that your 3DR Power Module is bad, or you do not use the 3DR power module.
After you calibrate the Power data, you will can arm the pixhawk sucessfully , but the message maybe display all the time ,ignore it. Because this is just a prompt message of PX4. If pixhawk can read volate data from 3DR POWER module, it can arm sucessfully.
If do not have 3DR power Module or 3DR power Module is bad, how to use pixhawk?
Download Mission planner to upload and use ardupilot firmware. Ardupilot can use without 3DR power Module.