I bought a second hand phone for the spare LCD. When I opened it up I noticed the LCDs were different but I fitted the new one anyway. When I switched it back on I had the dreaded white screen that a lot of people get. Stripped it down and reconnected the LCD flexi tape to the connector and after about 30 times eventualy it worked. Maybe that's it then just keep messing with the connector 'til it works!
After a while I found that you don't have to rebuild the phone completely as you can hold the battery up to the contacts and press the switch.