Question, when you are pushing down on the woofers cone, are you pushing on it from the dead center of the woofer?
If you are pushing it from off-center it will make the coil rub against the pole peice regardless of the woofer being good. If you have not put an ohm meter to it yet or dont have one. Grab a 9 volt battery (cordless drill battery or even straight 12v from your car will be fine) connect a set of wires to the battery and just tap the wires to the terminals on the woofer. If it moves you got install probs, if nothing at all happens and you have an open voice coil. Dont worry this will not hurt your woofer. This is an old install trick to test polarity of a woofer (depending on how it moves (in or out) to dc voltage)
Could just a be bad glue joint in the woofer's voice coil/ cone joint (spot where the coil former and cone connect) the leads are just a small single copper wire at this point and are very fragile, if a shortage of a rubbery expoxy/CA(the glue most manufactures use) does not cover the wire, it will break, thus leaving you bassless.
If you tap on the cone and you a hear springing sound in the coil you may have bottomed the coil against the backplate and broken the coil that way too. I do not think you overpowered your woofer at all. Distortion kills woofers, 80% of bad speakers are killed by distortion. In your case sounds like a defect in the product.
