I have a SmartUPS 750 here that I can't seem to get working properly. It's reading "Connect Battery" on the screen, so I swapped the battery with a new one, and the message persisted. Again, I swapped in another brand new battery, and same message. I've checked to make sure it's properly connected. The screen appears to jump between "Connect Battery" and the battery stats, almost as if the connection is loose (which is my suspicion). Anyone else experience this before ? Do I need to reset the unit somehow ? Thanks.