Headquarters: nelso knows about the lair, repeat nelso knows about the lair. Proceed neutralisation. ;) More seriously, I think the simple reason is probably

Headquarters: nelso knows about the lair, repeat nelso knows about the lair. Proceed neutralisation. ;) More seriously, I think the simple reason is probably just that the flash memory doesn't work anymore but the OS and its apps maybe were installed in the ROM which has survived. Dunno... just a theory.