Glad the new one is working well for you! Wish I'd seen the post a while ago and could have been another voice telling you to swap it. I haven't heard of the FNX doing that without getting hot first though. I hope that this is not a new glitch emerging now. Mind me asking what about is your serial number? Mine is in the 1600's and no issues for me. I believe the heat failure serial numbers were identified somewhere on this forum.