Make sure you have an original OEM charger for the MDA. Many of the knock off chargers don't provide the right amperage for the device. What happens is that since the phone is completely dead, it can't regulate how many amps the battery should get during the charge and an incorrect charge current won't charge the battery. I'm guessing that someone sold you a Motorola RAZR charger or another knockoff made for the RAZR. This might charge your phone when the battery is working, but not when it's DEAD. Also you won't have luck plugging it into a computer USB cable because, again, the phone can't tell the computer what charge to send and most computers only produce <0.5 amps in the USB port.
Get a charger that states it is an OEM (original eqipment manufacturer) device or one that is specifically designed for the MDA (or Cingular 8125). eBay is full of them.Bad charger
(probably won't work for a dead battery)Good Charger
(correct amperage and designated for the MDA)