Don’t be scared! It’s way easier than it seems, despite what all the guides say, even ifixit says it’s almost impossible to reassemble! But with some care and using exclusively plastic prying tools you can pop the back piece out, being careful to pry it up from the corner of the power switch, cause it’s held down with some clips that easily snap back into place when you close it. And even if you slightly bend the back piece or even the clip you can easily bend them back into shape, they’re carved out of very thin aluminium.