You get a voltage like 11.4v when the BMS is switched off. Replacement batteries are normally dumb and they don't allow remote switching, but you haven't given any details of what it is or where you got it from, so I can't confirm that.
Assuming that it is a dumb battery, the question is why the BMS is switched off. The common reasons are that the on/off switch is off, it's drained flat, one cell is faulty, the BMS is faulty, multipin connector not in properly.
Even with the BMS switched off, you have the same voltage on two pins, which could mean that the pins are doubled up like I explained in your previous thread. You need to confirm that by setting your meter to read continuity (beep), then check between pins 1 and 2, and 5 and 6. If they are connected in pairs that would be very nasty for your electrical system if it was trying to communicate through pin 5.