I have the same problem and I went to the service center of Huawei. 1st method is they reprogram my phone it was okay for 2 days and the problem returned so the 2nd method is to change the main board which took me 2 weeks to wait because they have to order it from the main store and the changing of main board took 2 hours. So far my phone is okay now and the new main board has 3 months warranty. Total payment is almost 30USD