There’s a few steps we can do first: - Make sure the official charger and cable are working with another device if possible. - Power cycle the device by holding the Power button for 20 seconds, repeat this 5 times. - Attempt to start the phone by holding down the Power button along with the Volume down button to start recovery mode and performing a factory reset. If these do not solve your problem, please follow the steps provided below: 1. Let your phone rest for 12 hours (do not charge) 2. Charge with the official charger and USB cable for 6 hours 3. After 6 hours disconnect then reconnect your device to the charger, a low battery screen should appear 4. Do not attempt to boot device, please allow the device to charge for 1 more hour. 5. After 1 hour, your device should be ready to boot and power on.