Sounds like you have either a charger problem , a cord problem or a port problem . Start by inspecting the charger port . Is it loose or damaged is there dirt in the port if there is clean it with a wooden tooth pick and compressed air. if its damaged or loose you may need to replace it . If alls well with the port check your cable try a different one as well as the charger. If you were getting the message the charger wasn't original it may have been that the charger or cord were failing and that its time to replace them. One last note Has the battery ever been replaced ? If not this is an old phone and a new battery may be in order. Hope this helps