Although a white screen may appear to be an issue at first, this is not always the case. With new parts the phone is not able to instantly recognize the new hardware, therefore causing it to slowdown and act strangely. The best thing to do in this case is to perform either a hard reset or a standard factory reset. To perform a hard reset simply hold the power and home button down at the same time for 10 seconds or until it reboots.
Note** be aware that performing a hard reset whilst the device is plugged into your computer will wipe out all your data on the phone.
If after a couple of tries the problem still persists then please feel free to contact us via any one of our methods and a resolution can hopefully be achieved.