I have a 378 and I believe all the fireplaces installed, are manufactured by Dimplex, and they have a web site @ Dimplex - Home Page
In regards to other switches there is a switch and lite indicators behind a panel at the bottom of the fireplace. The panel cover is on a hinge at the bottom of the panel. Just grab the top , approx 2 - 3 inches from the bottom of the fireplace and pull out.
If this does not work for you, I suggest you go to the above web site they have manuals available for down load.
I hope this helps