Try to get boot recovery mode where the colors of the letters are red and wipe the data factory reset. Everything gets erased like it just came from the factory. A little deeper than the factory reset in the phones menu....but no harm to the phones settings. My u , 7 and backspace buttons weren't working and now they are after I did the recovery boot factory reset. You'll have to Google how to get the recovery boot wipe data menu on the ZTE I'm not sure exactly how I access it. But good luck