You can skip steps 18-23 by desoldering the 3 battery connections and unsticking the old battery from the copper film that is stuck to the backplate with an opening tool at step 17. The battery will curl but this isn’t a problem so long as you don’t bend it too far. Slide the old battery out from under the logic board. Use the opening tool to smooth down the copper film if it has lifted by pressing down firmly and pushing the blade from centre to outer edge. Slide the new battery beneath the logic board and wrap the ribbon over the top. Solder up and reassemble.