Be careful when taking the back panel off. The speaker is connected to both the front and back panels, and may get pulled out if you are not gentle when lifting the back panel away.

Slide the plastic prying tool in between the front and back panel and pry them apart on all 4 sides.

It may be easiest to start on one of the sides, and work your way around the device. The bottom, with the ports, is the most difficult side and can be saved for last.

There are small latches that make this difficult. Moderate force may be required to separate the two panels.