We had a problem with ours in that it would not shut off. I had to trip the breaker to turn it off. No cool down period so not a good option. I sent an email to Dimplex and they suggested a relay board. Ordered it and it fixed the problem. It took longer to get the fireplace out to get to the relay board than to replace it. The cost of the part was ~$45 including shipping. No soldering just push on spade lugs.
You can find troubleshooting documentation online at
https://www.dimplex.com/en/. You may need to locate you model number by pulling the unit out. The info is located on the top panel.