I have also had the white screen of death.
Here is my story...
Last week I dropped my iPhone 3GS.
It slipped out of my pocket while I was sitting on the couch.
I have dropped my phone before, but it is (or I should say was) in pretty good condition. You wouldn't know that it had been dropped, let's put it that way, no scratches no dents or cracks.
My phone fell approx 10 inches.
Right away I knew something was wrong, there was a popping type sound. I picked up my phone and tried to turn it on. The screen was white. I tried to turn it off but couldn't. So I force quit it. I then couldn't get it to turn back on. I was so mad at myself, but mostly just really really sad.
I scoured the internet for answers and came up with a few, button fixes this and that.
I took my phone apart, I mean I took off the digitizer and LCD, I also took out the logic board. I then put it all back together. Guess what? it worked! It came back on it synced with my mac and it all seemed good. The battery had been completely drained, even though when it fell it was just over 90% charged. I kept it plugged into the computer and it charged up to 100%, I then unplugged it, used it and all was good, everything seemed to work fine, I could make calls, receive calls, texts pictures, videos etc.
My next test, turning the handset off then back on.
It failed that test. I then kicked myself, why turn it off I had it working!
I tried what I had just done and again took the phone apart and put it back together. No good, all I had was a white screen.
I tried to clean the connectors. No good just a white screen.
I tried my daughters LCD. No good, her LCD went white, I by now was bricking it thinking I'd now messed up 2 iphones, when I put her LCD back in her phone it worked! I was so happy.
It didn't stop me putting my screen in hers though. No good, all I got was a white screen. I then put her screen back in. Her screen was now white as well!! That however was fixed with a reset (home and sleep combo). So I hadn't screwed her phone as well.
Well I ordered a new screen on the off chance. No good just a white screen UNTIL I did a reset with the new screen in place. Home and sleep combo, guess what? It is now working!!!
So I am assuming after changing the LCD for a new one that you still have to do a force quit due to the phone still actually being on when you take the front off.
I can't guarantee that this fix will work for everyone, but it did work for me. So try it it just might work for you as well.