Before separating the back cover, note the following:

There's a seam just under the back cover panel. Don't insert your tool here.

Insert your tool completely under the back cover, so it's between the frame and the underside of the back cover.

Insert an opening pick under the bottom left corner of the back cover and slide it along the bottom edge to release the clips and separate the adhesive.

You should feel and hear the back cover clips release. If you don't, insert the pick deeper and try again.