The back side of the PB360 has got two covers - upper and lower. The lower one is the one we're looking for to open.
Put your two thumbs on the lower cover and pull it a little bit towards yourself, it slides open and then you can take the cover off.
The reset button is in a pinhole to the right. Don't forget to connect your PB to the power source (PS or outlet) before re-setting.
Have a nice e-reading
.