Yo! Made an account because of this thread. Same problem here I think.
As soon as the unit gets power, front panel just says power on / harman kardon. Nothing happens. Unresponsive to on/off button on top and remote.
Any fix yet?
Could be a number of things all of which are not diy or cheap enough to be worth repairing.
I would suggest you disconnect the speakers and try turning it on. If there is a bad speaker of short in the speaker wire that could cause the unit to not turn on.