I used a free HEX editor for Windows (HHD HEX EDITOR).

http://www.hhdsoftware.com/Products/...itor-free.html

First 4 bytes in each file looks like '0710' (HEX: 0x30 0x37 0x31 0x30). It's the software version number. Changed it to '0720' (HEX 0x30 0x37 0x32 0x30).

I also modified the navboot file using gifextractor, and changed the header text to reflect the new firmware revision.