Sounds like your radio is shorting out and popping the fuse. Is your radio stock or aftermarket? Pull out the radio and look at the RED and YELLOW wires (if its aftermarket), check and see that they're not pinched by anything and that they're not cut open and touching metal.
YELLOW wire: Constant power (always live, even if the cars off).
RED wire: Switched power (only live when the ignition /car is on).
If the wires look ok, your deck may be fried internally. Although this is what fuses are meant to prevent, if you wire the speakers wrong and introduce the radio to an ohm load lower than 4, that'll cook it. Wiring a speaker backwards (putting the + to the - and vice versa) won't cause this low ohm load situation, so don't worry about that. That'll just kill the bass output of the speakers, that's all. Or if the radio gets really hot under normal operating conditions, although that's rare, will cook it too. Smell the radio, does it smell burnt? It's like a stinky, carbon scorched smell. Don't confuse the "fried radio" smell with the "warm electronics" smell, they smell quite similar to someone who hasn't had alot of experience in this area.
So its either:
1. Power wires from the deck are touching metal (ground)
2. Fried radio