Sorry this response is late.
The “Write Parameters” is in the CONFIG area for those parameters mentioned above if they are changed.
You bought something like this?
I can think of only two other things to check:
A. Reflash the firmware. If the latest version doesn’t work, try an older version.
B. Test if the board voltage sense pin is dirty or faulty. You can power the board via the RPi, then apply a small voltage (<3v) to the sense pin and watch the HUD or ‘Measured battery voltage’. You can use a bench supply, or a 3v coin battery or AA. Be sure to connect the board ground. Avoid a higher voltage that might ruin the board. Make sure to check the board pinout diagram so you are touching the correct pins.
Here is a reference to the power pinout, so it looks like it is pin 4.
https://ardupilot.org/copter/docs/common-pixhawk-overview.html#common-pixhawk-overview
If the test fails, or just want to get a new board, I would contact Caleb.
https://dojofordrones.com/contact
Also see this, though not directly related:
https://community.dojofordrones.com/t/issue-configuring-battery-monitoring/942