MPC-20 power options

I was able to upgrade firmware and the light changed status from from blinking to steady red. After that I tried to power the MPC-20 with a 5 volt wall charger and the light blinks continuously and is not detected by the pedal config software.

Can the MPC-20 be powered from a wall charger or does it always need to be plugged into a computer via the USB port for power?