If it keeps blowing fuses, then it's most likely one of three things: short in the cable, power supply cap or output resistor.
To trace a short in the speaker wiring, check that no cable connectors are touching. If ok, then disconnect all cables and turn on unit in non-bridged mode. Then flip the switch to bridged mode (if the manual says otherwise, then forget it). If the fuse doesn't blow, shut down and reconnect with new speaker cables and check all connections prior to turning on.
If the fuses still blow, then the only thing to do is have it serviced - it's either a power supply capacitor or an output resistor that's shorted. If it runs okay on one side with the bridged switch off and still pops a fuse when the bridge mode is on, then it could be a resistor short.