If your ZTE Blade X Max LCD is damaged—dark spots, cracks, unresponsive to touch—and you have already finished troubleshooting (insert link here), then you may need to replace it.
This guide requires removing the back of the phone, which is not meant to be removed by the consumer. You will have to use heating products to complete this guide. If you are using the iFixit iOpener, or a heating pad, be sure to follow the instructions for that particular product.
To remove the battery, you will have to heat it. Be sure not to overheat the battery. If you do, the battery will swell and be rendered useless.