I suggest you take it for repair. Shutdown:
1, Open AssistiveTouch function: Set -- General -- Accessibility --AssistiveTouch-- Open AssistiveTouch function.
2. After opening, there will be a small black square on the screen
3. Click AssistiveTouch white dot, select \"Device\" and hold on to \"Lock screen\". Hold on for more than 2 seconds, and then slide the slider to the right to turn off the device. If it is a national bank machine, charge it first (because it cannot be turned on without electricity), and unplug the data cable when the charging icon turns green. Press and hold the Home button again, and then connect the charging cable to boot.