The .aos is a crypto compressed. Thus, it can be opened, but you have to have the key. It is not like your basic firmware. Archos is really protective to their FW. They have been since Gen4 product line. (The 28/32/43/70/101 is Gen8) Even though Android is an Open Source model. It does not mean Archos will let you play with it. If interested, go over to the XDA site and search on Archos and aos. It will provide insight how to open.