It is highly unlikely to have a shorted transistor unless there was some mode of damage to begin with. Some examples are:
Solder bridging pins on the transistor
Shorting the transistor while trying to measure voltages on its pins
Installing an incorrect transistor on the PCB
I would suggest running the amp without the 6080 and examining the voltages on terminals 1 and 5. Do they run stably?
Solder bridging pins on the transistor
Shorting the transistor while trying to measure voltages on its pins
Installing an incorrect transistor on the PCB
I would suggest running the amp without the 6080 and examining the voltages on terminals 1 and 5. Do they run stably?