I read the info on the forum from 2009 about the factory reset button, and how it didn't work.  So I emailed DSE help and support and got it sorted.  I couldn't reply to the forum because it was closed off.  
I got mine to work using factory reset doing the following:
You have to hold it down for 20 seconds, switch off at wall WHILE STILL HOLDING RESET BUTTON, then turn it on at wall again, while still holding reset button, and then keep holding it down for another 20 seconds.  Fabulous, it reset perfectly.