Problems
- Only Display Light (Blank Display)
- Not even display light (No display at all)
- Touch Screen not working at all.
- Slow touch response.
Workaround
- Restart your phone and check.
- Go with a Software update, as most o0f the time this issue is also resolved by software update.

- The very first thing that you should do is to check Display connector and check for any loose end, if it is fine then check it with another good LCD screen.
- If Display connector is faulty or damaged, replace it and check it with the same or some other good LCD screen.
- If that doesn’t work then check the filters of your display connector.

Sometimes it happens that your iPhone 4 only gives display without back light, and in order to overcome this problem all you have to do is to check the intensity / brightness of your phone, if it is less, then increase it as per your needs. If this step doesn’t work for you then:
- Remove and re-plug display strip.
- If the above step fails then check the connection from “Display connector pin†to “Capacitor†and then to “Backlight ICâ€. Put jumper if necessary.
- If the connection between display connector pin, capacitor and backlight IC is fine then replace the display light IC, as display light IC is the cause of this problem.

If your iPhone 4 touch is not working then:
- Restart your iPhone and verify whether it is working or not.
- If it is still not working then re ball or replace touch IC of your iPhone 4.