Hi! My name is ***** ***** I will be assisting you. Let's get started!
Before, we get started, there is some good news that your phone is covered under warranty so worst case scenario is that ZTE will repair/replace it for you.
With that being said, please plug in your phone and while it is plugged in, hold down the POWER BUTTON until your phone restarts. After the restart, allow your phone to charge for 10 minutes and see if it holds that charge.
Please let me know the result