@imgermg If you can turn on the board you may be able to use the OWCE app to check voltage.
https://owce.app/install

If not the only other way to measure is to take it apart and measure with a multimeter at the battery connector.
I have labelled the 2 pins you can measure without unplugging the battery but be careful not to short them.
3530d501-383b-426c-b668-51187345068c-image.png