This solution is very usefull for sprint 7700 dual sim phone repair. This is sprint 7700 dual sim charging solution.View the picture and work step by step.
How to do this work : If You see your phone is not charging then first check your charger next check phone's charging port.If they are ok but problem still then check this charging ways.If charging ways is ok but problem same then check and change red mark parts.This solution also work,Charging showing but charge not store.