Can't turn on without batteries inside

My MPC500 isn't able to turn on when there are no batteries inside even thuogh it is connected to a power supply. Is this how it's supposed to work? Also, I noticed that the Battery voltage when i press "status" on the MPC is decreasing even though it's connected to a power supply. Can anyone tell me what's going on?

Edit - ignore what I said! Didn't realise the portable batteries was separate to the ac adaptor.

coulld b a faulty power supply

It doesn't need batteries to operate. Just the ac adapter alone should do the job.

But your problem sounds like a glitch in the system. You should reinstall the 1.31 OS from akaipro.com its free and there, they'll show you how to install it.

Good luck and if all fails then inhale an el.