From what you have said it is failing to light and the control locks out , so the stat is telling it to come on. That control is way overpriced and is way out of line. Considering on how much they are going to charge you to fix it, I would consider replacing the furnace. The G24 in my opinion was a very poor furnace and am glad we only put a couple in. I wish I could get $700 for a service call, where do you live?