I would like to ask you some questions in order to probe to find the best solution.
Have you attempt to charge device with different lighting cables, power adapter, and power source?
Does iTunes recognized your device but iPhone display present a blank-black display?
Switch from silent to ringer and if it vibrates it means your device iOS is on and running and you will need a display replacement.
Check the charging connector for pocket lint or damage on the charging pins.
If lint is found clean with nylon brush (dry tooth brush is fine) if damage on charging port is found then a whole unit replacement will be necessary.
Attempt to DFU device using iTunes
Contact Apple support in order to make appointment.