How to replace a iphone baseboard? Or do i maybe have another problem?

I have a iphone 5 and recently got it wet, it will not connect to my verizon or wi-fi but will dectect Wi-Fi signals and show them as avalible. I took the iphone into my local phone repair shop (part of the kracked chain) andthey told me that is was the antenna for sure. After replacing the antenna and putting a new sim card in the phone it still give me the "searching" message ehere my 3g 4g reading should be. I a inclined to belive that my sim card reader got fried but the guy working at kracked insisted that it wasn't the problem and that my baseboard was fried and i should give up on the phone. I have some knowledge about iphones and if the baseboard was fried wouldnt the iphone not be able to function anything else properly? It will run everything else on the phone just fine except connect to any form of internet. Also, if my basebiard is ruined could there be anyway to replace it without losing this phone. And any of the data on it? Also, if the baseboard was corrupt wouldnt some of my information on the phone have been lost/damaged? Because all of my 15,000 and somthing pictures, music, and all offline stored data for apps is just fine. I have seen replacement basebords for sale and i'm just not sure on the details surrounding replacing one or if it is possible. I have one more question, if the iphone is shot is there any place that will transfer all of the data to differt storage and then transfer it back.to.a brand new clean and clear one? I aplogize for asking so.meany questions and i really appreciate your answers i really do. If possible i would really liie to keep this specfic phone because it has much sentimental value. I sincerly aplogize for any misspellings.random peeiods and odd words as i'm typing this from my nook. And it. I haven't quite gotten used to the keyboard yet again. Thank you so so much for any and all of your help! I reallu do appreciate it completly!

First, store all your information in icloud, or itunes. Second, insert your phone in itunes and update the operating system. If that doesn't work try and restore your iphone to original setting by choosing the option in itunes. If that doesn't work i really don't know what the problem would be. As for your question about the basebord (Motherboard) being fried that is correct. If it were to be fried your iphone wouldn't work at all since all the main components are attached to it, including the processor, and screen. Also as for replacing it, i wouldn't really take the time or money to do so, as most of the motherboards are just to cheap to function as good as the original one.

You ruined it. Lol!