White screen after opening the phone

I have 3gs iPhone,in a middle of a call it says No sim card installed I tried every possible solution : restore jailbreak and every thing.....

So I decided to open the phone to have a look on it components and see if something went wrong....

but the lack of experience helped find nothing.....

so I decided to use it as an ipod ..well.. I had put the phone together again and I did succeed but when I turned it on all I see it a white screen,

when I turn it on, I can not see an apple logo , but soon after two minutes I can see the white screen, Itunes recognize it and it is charging ,

I tried these solution from the guides here :

1-Hard Reset

2-Replacing the LCD

3- Changing the battery

4- Disconnecting the logic board for half an hour and more even

5- Restoring the firmware

6- Restoring from a backup

7- Changing The Display assembly

8-Cleaning the logic board

9-Searching for any thing wrong with logic board after removing it adding to the removal of the metal things there,

Still When I turn on the phone its white screen

help please,this phone is driving me crazy,

Thanks in advance