Remove the old battery adhesive from the rear case using tweezers and high concentration isopropyl alcohol with a lint-free cloth where needed.

If your battery doesn't come with preinstalled adhesive, use Tesa tape to reattach the battery to the rear case.

Before installing the new battery, test it by first reinserting the logic board, connecting the button control cable ZIF connector, and the LCD press connector. Then remove the battery blocker and reinstall the battery connector screw. Power on the device to ensure it still works. Go backwards through this step and then glue down the battery.