After Water, Backlight K O and software stay on the APPLE

Hi,

I have an iPhone 3GS and he take water......;(

I let him drying few time (3 or 4 days)

I try to power on but nothing happend.

I plug it on my computer and let charge....

result: no Backlight and it Stay on the Apple Logo. In spite of that, I can restore It fully but he always stay on the apple logo.( Geohot's head appears when jailbreak...)

I Think that i must change the display assembly for the backlight but If i change it i'm afraid to change another parts( the iPhone motherboard or logic board)

I just want to know how to fix it pleaseee Help I've lost my precious!!