The unit consists of 3 main parts:

The bottom case, which holds the battery, USB charging port, as well as the rubber side buttons

The top case, which holds the mainboard, LEDs, and the top rubber buttons

The screen which is glued to the top case and connected to the mainboard via two ribbon cables on the left hand side of the device

To soften the glue use a heat gun (at low heat) or hair dryer and heat up the edge of the top case

Use a small metal prying tool to pry open the device. This will take time and patience. The device is glued together like a tank!