I defer to the carrier's support but have a trick that has helped in the past in regards to the battery.

I remove the battery then press and hold the power button for a full 60 seconds. Then release, pop in the battery and DO NOT TURN IT ON. I place it on the charger and wait for the LED to tell me it's done.

Since it's not on, the CPU is not running so the basic charge system works. If it doesn't charge then there is something wrong such as a failed charger, battery or phone.
Bob