If I change the motherboard on my iPhone6s what will happen?

@omar12708 the logic board is for all intent and purposes the phone. Replacing that board is like a different phone. Not sure what you are planning on, so give us a bit of a hint of what you are up to.

"I have an iphone 7 with icloud locked.

Now seller is not giving me full details. I know that I purchased an expensive paper weight.

Now I want to make my phone in running condition. Is that possible if I change its mother board/logic board to use it normally.

Will that phone start as new device?

Can anyone help me then i will go for board purchase.

Thanks in advance."

You have to make sure you change the logic board (motherboard) with an iCloud UNLOCKED logic board that includes the original home button for that particular logic board, or your touch ID won't function correctly. Also, this may sound like a dumb question, but have you changed the battery yet?