Did you plug the charger directly into the outlet or did you use a power strip with surge protector or power conditioner? I always use a power strip. Ship's power, while reliable, is not stable (clean) and there is a possibility that there was a power surge that fried the phone.
A power surge, malfunctioning charger or change in polarity of the plug would explain why the phone and the battery were fried.
It could have also just fried on its own.
Draining a cell phone's battery (Nickle or Lithium) isn't a bad thing and should not cause the battery to fail. It should accept a charge even when fully discharged. The "battery memory" theory: "If you continue charging a battery without completely discharging it then it will cause the battery to "think" it's discharged even when it isn't." This theory hasn't held up in testing. Nickle batteries just don't last as long and get to a point that they won't take a charge.
One thing that will cause your Nickle battery to discharge faster is using a car charger. These are quick chargers and while they charge the battery they also cause the battery to discharge faster. Don't use your car charger for regular charging.
Lithium batteries have less problems.
Mike (Always uses a power strip/surge protector on the ship)