On the cellular model the sim reader needs to be disconnected as well. It’s located just below the battery connector and has a little piece of black tape covering it.

There are two antenna connectors on the board in this upper area on the cellular model that need to be disconnected as well.

On the cellular model be sure to disconnect the two antenna up by the front facing camera on the board as well as the sim card reader connector by the battery connector.

The battery connector is actually the smaller connector to the right of the one highlighted.

If your replacement screen comes with the frame you’ll need to to be sure to transfer over the other small components including the volume buttons, mics, ear speaker, and vibrating motor as well.