White Screen of Death after Bake the iPhone

Hey guys!

Last month my iPhone´s (4) GPS started to become intermittent. Sometimes it worked, sometimes its not. As I live in Brazil and bought my phone in USA, I had nowhere to go, no warranty support, so, after tried so many restores, Cydia tweaks and long hours in open places, I decided to open the device and give it a shot, try to find some fix by myself.

I opened the iPhone and did everything I could. Disassembled it by complete (a few times) and checked every possible cause for the issue, but found nothing. So, I saw somewhere in internet about the "Oven Trick", that consists in open your phone, take out the main board (PCB) and put it in an oven for seven minutes in a temperature about 190 Cº. Theoretically, the heat can melt the solder and fix microfissures in the phone's main board. Well, seens it's true, my GPS is alive again!

Despite the GPS been' workin' fine, now I'm dealing sporadicaly with the "White Screen of Death": when the iPhone gets to sleep state and I press the "Home" or the "Sleep" button to wake it up, the screen turns to complete white, but I'm able to unlock the gadget, use the apps, play music (I can hear the sounds) and even conect with iTunes, but I can't see nothing. I'm just able to make it come back to normal opening the iPhone and cleaning the digitalizer and LCD connectors. When I do it, the iPhone works flawlessly for a few hours. If someone can help: do I'm just gettin' a bad contact and not assembled it right, or yes, I did worst and burned this part ot the PCB?

In time: hard resets doesn't help me, they do nothing but keep with the white screen. A restore was not a good option too, things didn't change. What I have to do, like I said, is open the phone and clean both connectors (digitalizer and LCD) for things go fine for a while. Last time I opened it, my camera stopped workin' too... Well, guess I'm killing softly the iPhone 4, but I'll fix it or die (I mean, kill the phone) trying!

Thanks in advance and sorry for any english mistake.