Changing the motherboard can remove iCloud

If you change the logic board with a other logic board that is iCloud free it is ok. The iCloud lock is in the logic board.

"You actually may be in a better situation then most people. Depending on how much he remembers (or if he can reset the password), he can get the phone working again. If that’s not the case or it actually came from eBay/Craigslist/OfferUp/Mercari, read on. However if you have a proof of purchase from an authorized reseller Apple will remove the lock.

Generally speaking, the cost of a replacement board is about as much as a intact iPhone. Since you’re getting a new phone by replacing the board anyway since the IMEI is going to be completely different (plus the downside of the SIM tray IMEI not matching, so nope can’t verify the IMEI# with the tray anymore, and give buyers a red flag the board is not original) often times unless you can strip it of parts, you’re usually better off dumping the iCloud lock phone “as-is” to offset the replacement cost, sadly. Let's just leave it at he won't forget ever again.

The other problem is there are NO GUARANTEES the new board is clear to activate or it isn't hiding a payment plan (which will inevitably be defaulted on and your new board is now blacklisted too). T-Mo phones are notoriously bad for this, so NEVER EVER EVER BUY A T-MO PHONE (iOS AND ANDROID) WITHOUT CHECKING THE IMEI# IF YOU INSIST ON A “LOCKED” T-MO IPHONE WHEN YOU CAN LITERALLY USE A UNLOCKED PHONE WITH THEM, OR BUY AN OLDER ONE WHICH IS FREE AND CLEAR. Between the high risk of a IMEI financing block where someone became a deadbeat on their payments and T-Mo phones being risky, this repair is best skipped. The 2.5-3 year payment plans do not help.

Since the board swap basically makes it a new phone and you’re probably going to deal with the same issue, you’re better off just finding a clean phone and replacing the entire thing."