I successfully replaced the battery in my A1954. But I stopped at step 40 and then I just pried the old battery with the plastic cards that came with the new battery and some isopropyl alcohol. Next step I pried the logic board upwards with a blue pick around the screw area. The board needs to flex upwards more than you're comfortable with in order to make room for the new battery connector to slide underneath the pick but over the screw hole underneath the logic board. I dint't really feel like gutting the entire housing of all the parts but I was risking damaging both the logic board and the new battery. So do it at your own risk.

used this guide and the charging port guide to swap all the parts from a cracked housing to a new one. Thank you!

This step needs to be done before you mount the battery, if this is the reason why you open your iPhone. The battery connector points up and makes the blue film to curve up and not align properly with the edges of the phone. I know, small details, but this is making the job even harder than already is. Maybe a cut out in the blue film, for that area, would have been useful.