My experience (upgrading to a Crucial 2TB) - slow and steady wins the race
* Step 3 if difficult, play along other seams with pick
* Step 5, just uncover the screw when peeling back the shielding, no need to remove it, just get room to take screw out
* Step 8, disconnecting battery is best done by using a spudger to push the connector out on each side firmly, back and forth a little at a time
* Step 11, similarly with the SSD shielding, wiggle each side, use a tweezers to help
* During reassembly, firmly get battery connector in with back and forth process. When putting screws in, align correctly and do not cross thread, you may have to open up again in the future.
* Used a small powered USB-C hub with reimaging, took quite a while, just sit and be patient