Hi,
Try starting the phone in [https://www.hardreset.info/devices/zte/zte-tempo-x/safe-mode/|safe mode] and check if it works OK or not. If it doesn’t happen when in safe mode then a ''downloaded app'' is the cause of the problem. The trick is to find out which one. You will need to uninstall each ''downloaded app'', one by one and test the phone in normal mode between each uninstall until the phone works OK. When it does then the last ''downloaded app'' that was uninstalled was the culprit.
If it still happens when in safe mode, try a factory reset, using the phone’s factory reset feature and check if this resolves the problem.
''Be aware that a factory reset will erase all your data and downloaded apps. It will restore the phone to its’ factory default condition, so if you decide to do this ensure that you'' '''backup''' ''the phone to a computer or the cloud using the phone’s backup feature'' '''before''' ''performing the'' '''reset'''
Once the reset has been completed, check if the problem is still there or not.
''If the problem is still there,'' you have a hardware problem. The phone will need to be opened and inspected and tested as to the cause. Is the phone still under warranty by any chance? If so get it fixed under warranty.
''If it is OK'' and you’re satisfied that it is working OK, restore the phone to what it was with the backup that you made earlier, by using the phone’s restore feature.
Once it has been restored to what it was, check that it is still working OK. If it is then the reset has resolved the problem.