iPhone White Screen (not the usual)

[lizarnator]

i replaced an broken iPhone 3GS screen with a new (used) screen. then i got the white screen.
tried the button holding (home, vol up and sleep), worked the first time, but after that it went back to white screen and now no luck with the combos.
now i have tried the screen that went white on a different iPhone (working) and it was white on there too.
so i thought it was this particular lcd, so i put a brand new one in the original iphone, but it went white too. now this lcd is also unusable with any other iphone.
also, after putting the white lcd screen on the second iphone, i now cannot get any screens to work on this phone.
so i am stuck with 2 iPhones that seem to have problems on the logic board, causing white screen. and multiple screens that cause white screens on logic boards.
maybe a fuse has gone on the logic board?
can anyone help?
cheers

 

[aplees]

I fixed a 3gs a few days ago and replaced the digitiser, after putting it all back together again i got the white screen as well, tryed for days to fix it to no avail.

i on the last atempt thought sod it and left it on charge and after 5 mins it came back on. for some reason every time i reboot it i get the white screen and it starts and loads every time after 5+ mins. just plug it in and leave it a while see what happenes.

This phone has been restored as a "new device" on 5.0.1 several times and still the same outcomebut it works after a while of waiting.