Thanks for the suggestion. I explained the situation there and the reply was to use the tftp flashing method described here.
Unfortunately, all attempts failed to successfully load stock firmware into the router (documented in this topic). Most of the time the file transfer timed out or, at best, it would transfer some of the file and then report 'transfer cancelled'.
Seeing that the technique wasn't working, I resorted to the 'pin short' method you described here:
I'm pleased to report that it worked on the first try. Now the e3000 is back to stock firmware.
Many thanks for your patience and expertise.