I would make this difficulty “easy”. other than the load of fiddly screws, there’s no real obstruction or tricky disconnection to be done.
Yeah, not sure about “slide" the cable retainer… in the end it snapped off and out of the way. occurs to me I haven’t tested the camera yet, but the drives worked.
Just went through the replacement and the battery "plug" (step 5) on my replacement battery was slightly misaligned relative to the metal plate used to screw it onto the board. The plastic and "gold" "plug" was slightly askew on the metal plate, which meant that when the plug was inserted, the screw holes (step 4) were poorly aligned.
I managed to pull everything back into line using the screws, but the QC on these replacement batteries is a bit suspect.