If you are using the DC power supply that came with the PB5, the status light on the front of the box will be as follows:
On solid red – normal operation
Slow flash – track output has a short circuit.
Fast flash – No incoming data from the control bus jack.
Status light off completely can mean a few things:
The power supply is dead. Check the LED on the power supply brick. The color makes no difference. Only if it is on, off, or blinking.
A blinking power supply can be a problem with the booster or the power supply. Unplug the power supply from the booster but leave it plugged into the wall
If the power supply still blinks when unplugged from the booster, the power supply is bad. If the power supply STOPS blinking when unplugged from the booster, the booster is bad.