Wifi Logic board in a 3G Ipad?

I have an original Apple Ipad 1 WIFI that im pretty sure has a bad Logic Board. When plugging it in the screen flashes for second and nothing else happens. Ive tried doing the resets, and everything else and I think its just a brick. Ive found WIFI only logic boards on Ebay for $35. My question is can I install a Wifi only Logic Board into an Ipad that has 3G with Wifi in it? Would there be a problem fitting it in? Are the logic boards different shapes and are there cables in the housing of the 3G that have to be plugged in to work? Thanks.