what do you mean the thermostat locks?

Did you know that if you have a Lux 1500 thermostat, you can actually lock the panel so that you cannot play around with the settings?
I found that one out today...the hard way.
We actually had to turn the furnace on today...it's just too cold and rainy out now. But, when I was trying to re-program the filter setting, this little tiny lock appeared on the display. And suddenly, I couldn't do anything. Couldn't raise the temperature (it was locked at 68 degrees). And couldn't figure out how to reset it or unlock it!
Finally, we pulled the batteries out, and waited for it to reset on it's own. But, while I was waiting, I decided to google it, just in case pulling the batteries didn't work.
Amazingly, the first thing that came up when I googled "Lux 1500" was a post on BobVila.com, that told you how to unlock your Lux 1500. Apparently there were 52 people that found the following information useful...

Thanks to this website I found out how to unlock my LUX 1500 thermostat. As stupid as it sounds, just hit NEXT 3 times in a row and then hit HOLD. Sounds silly that the knuckleheads at LUX would put that code in but not label it anywhere, but they did; and this does unlock it.

I feel like a knucklehead for doing it...but at least I'm not alone!
PS - Pulling the batteries actually did work too.