Well if it's not a typo, the .5 for remote turn on is your problem.
Most amps will turn on with a minimum of 10.5v but 11v or more is the norm. I'm not sure if the psu unit your using has an amp turn on wire, or if your using it. But if it is only .5 volts on the turn on led, it definitely won't turn on.
Disconnect the turn on from the amp and use a digital multimeter to read voltage, that would be a good place to start trouble shooting.