Hello, was the device ever exposed to a liquid submersion or spill? Was the device dropped? Is the device running the latest software? If the phone was wet it could be corrosion on the pins under the LCD and Digitizer connections. If your device is un-insured, and you have to the tools and are comfortable you can try a few self repair troubleshooting methods. If you are not comfortable I would recommend taking the device to a repair shop. But if you are comfortable, try disconnecting the battery, the LCD cables, and check for any noticeable corrosion or damage. Refer to repair guides on iFixit's website for nay help you may need opening the device. Follow the steps carefully.