One of the very common problems with the MPx220 was the charging port breaking. The phone may still work even if the phone won't work. I had this happen to my old MPx220, and I used one of
these for a while until I got the phone fixed under warranty. It works really nicely if you have an extra battery, then you can just switch them out when one is dying. I'd get it and charge the battery, then see if the phone will turn on.
Another thing you can try is seeing if your PC will recognize the phone when you plug it in to a sync cable while pressing the left direction on the d-pad without the battery in it. If your PC recognizes te phone, there's a good chance you can revive the phone depending on what the problem is.