Help with low voltage battery Hadaen board

Hi,
We have a Hadaen 2022 year board, 2nd hand from friends, 800kms and still reasonably new.
Last 2 rides have cut out battery at 10kms range approx. We have since looked further at the battery after removal of ESC cover and taking out 16ahr battery. Looking at it looks to be 12S4P 21700 cells. ( I've built several boards in the past and vaguely know my way around). All cells in 4 blocks measure 4.18v give or take, but the total pack only measures 40.8v after full charge from the charger till green light on?
Suspect either BMS not working correctly or a circuit not working on the battery board.

Any one else have anything like this or suggest next steps?

Charger clicks off at 40.8v to green on charger. 3rd image

Cheers Jason

 

You are not measuring the correct points as you should be getting around 50v if fully charged. I would take a guess that is the voltage from the input to the output of the BMS (negative in and negative out). On my 10S board it measures around 38v when fully charged to 42. If you are sure that each individual cell group is 4.18 ish fully charged, then I would go for a ride once fully charged then look at the battery section of the remote info to see if one or more cells is low causing the bms to shut down under low voltage. Much easier than pulling it apart each time!