@Vietrider802 No worries, had a look at the vid :) If you can't probe your multimetre into the small holes in the black and white controller connector you can probe off the output terminals on the XT60 BMS side. I took one of your pics and annotated the ones you want to probe in volt mode. It might be best to probe within the connector since the connectors on the PCB are covered in a layer of protective coating that helps prevent corrosion via moisture and small amounts of water. Be careful not to short the terminals or your probes when doing this else it could blow the BMS. As there are 2 XT60's I labelled the one the battery goes in which we can ignore, that should always have voltage present on it. The other connector should only present around 43.5v and 63v (depending on charge level) if the BMS is told to turn on via that blue wire being connected to ground. It's a toggle so it doesn't need to be held in, only touched to trip it on and off as per my vid. Presumably when you connect that blue pin to ground on the black and white connector it should put voltage across that XT60 thus proving the BMS fine and pointing towards an issue further up maybe with the switch itself.