That's a possibility, but if the connectors were last off at the factory, they are very tight and should not get disconnected by themselves (you're more likely to need pliers). Worth checking though, as the midranges indeed rely on just those two wires between the boards.
If the condition of the midrange drivers themselves is unknown, try putting a flashlight on the fabric as shown on the attached picture, and peek if they have any of their surround foams left... still, they are connected as two series pairs, so at least two of them would need to already have a damaged voice coil to mute them completely.
The other speaker has an amplifier fault and needs service - it's anybody's guess what the exact problem is without going in there.