Once the two sides and the bottom are free, lift the bottom part of the cover slightly and push it up to release the headphone jack (yellow), and micro usb (blue) connections from the back cover.

The back cover should now come off leaving you with the insides of the Kindle Fire 7" (2015) exposed. You can see the battery (red), the main pcb (at top), rear facing camera (yellow), speaker (orange), and connection cables for the LCD panel (dark blue) and digitizer (light blue).

The arrows point to locations where five 3mm screws will need to be removed from. The blue arrow is where a white "s" sticker is found over the screw as what appears to be a warranty voiding tamper seal. Using a little heat allows its removal without damaging it.