Porgy, according to the pictures, your device looks very similarly built to my PB Touch Lux. On my ereader, I have to remove the black plastic part which is on the back to see the battery.
This plastic part is attached on the device by several clips. To open it, you could slide one of your nails or the blade of a little kniffe in one of the corners between the front and the back part and pull gently.
Have a look on
this page. The pictures will certainly help you.