The most common reason for a white screen is a loose copper ribbon-wire in the hinge of the phone. To fix this, you will need to take the phone apart. Start with back and then continue all the way to the hinge. The ribbon-wire has two spots for connection, so start by making sure it is all the plugged in to both of those ports if you do not see any obvious damage to the wire. If the wire is damaged you want to purchase a broken model for spare parts. For instructions on taking apart the phone and fixing to ribbon-wire visit [[LG CU400 Troubleshooting]].