My French is not that great, but here you go. D4 was faulty and has been replaced with a (1000v reverse fast recovery) diode. Make sure you disconnect the cables in the correct order or risk damaging the BMS! I have to ask a colleague if you want this information.
Thank you for the replies,
We found out that there was a diode that has gone bad (power for the processor). After replacing this diode the battery started working again.
We want to install the Rosen 200 aH wallbattery. But before we even wanted to try to mount the thing we wanted to see if it even works.
So we press the power button (without it being connected to a DC source) and nothing. According to the user manual it should still do something...