a weird problem with my iphone !

[iYazeedGh]

i was using my iphone (5 that is) and checking my g-mail suddenly my phone just turned off and i couldn't turn it back on, i went to a few electronics stores to diagnose it, some of them said ther's nothing wrong with it and couldn't do anything and some of them says the motherboard is fried

and couldn't be fixed, so i'm asking for your help , what's wrong with my iphone?

[jayctech]

Tried an Apple store? They'll probably just offer a replacement or something but..

[iYazeedGh]

right!! i should've went to an apple store i'm gonna see what they will say, i didn't go cause the other stores said it cannot be fixed that slowed me down, the problem is a couple weeks old actually, this shows how lazy i am   , thanks for your help.