Umm, that means it was exposed to moisture or is water damaged.
The water dmage may have caused the charg port on you D900 to short out.
If it is the charger port, You have 3 options.
1. get it repaired, warrant if possible
2. Get a new one
an external battery charger and charge battery separate from
phone.Another battery and charger will set you back about 10 dollars on
For more information and links to the parts check the following link below.
Samsung SGH-D900 charging problem repair