Keeps restarting with battery attached

I recently took out the (original) battery on my 2011 MacBook Pro with the intention of trying it in another similar model. However, I realised it was a slightly different year/different battery (2010). So, plugged the battery back in and now it’s showing 100% and only 5 cycles… except I know it’s at 0% and 500+ cycles. Also when the battery is plugged in the Mac will loop through starting up and will only start up properly and work fine… if the battery is disconnected. I’ve reset the SMC and even reinstalled the system (High Sierra). Is it time to give up on what (was) a perfectly OK battery? Any tricks I’ve missed? Thanks in advance.