Are you sure the battery is protected? It usually isn’t. The Quad charger should be and it’s good to see it haven’t blow up already 
Just switch the wires and try again. Maybe measure the battery voltage before inserting if it’s OK (this should apply for any battery).
I believe the guys at Seeed tested the Quad well but they didn’t check the separately packaged batteries. Looks like some questionable cheap manufacturer who doesn’t care about polarity… This is serious Beta issue and should be good warning for further products and testing before shipping.