Well I think that is pretty mean/greedy of them

As I do not know this particular box I can only give you some general advice.

1. See if you can find the service or technical manual on their site or the net and see if there isn't a reset switch or button.............it will almost certainly be inside the case, as it is pretty much an assumption that these boxes are kept physically secure., at least from someone with enough time to use a screwdriver?

2. Try a google search for the product/manufacturer then do a search within results for "reset" I am guessing that given the manufacturer's response there will be others that have had the same problem.

It may take a little while but I found out how to manually clear the non-volatile e-prom chip in a Dell Inspiron this way

Good luck

EDIT: I have just done a quick "google" myself..............the concensus is that it cannot be done for that model & software version...........it has to go back to netscreen who will charge you, or you take out a new service contract and get v2.6.1

Sorry to have to say it, but it looks like you bought a brick.