Why my phone cannot connect to intunes?

hai..actually my phone firstly no network, then can't upgrade ios, then when i reset all setting and make my phone like a new phone like first time i buy, my phone can't connect to itune and can't start like first time and no more to do,i just send my phone to shop, but all the shop i send said the same thing.my motherboard problem.and the last shop i send said motherboard problem and can't to repair because effect my processor ! so i wan to ask u, really when processor have problem the phone cant to repair? exit true? so what can i do? i really stress right know.