ahh! i get what you are saying! my solution would detect a blown fuse... but all i really care about is weather the heat sink cooler is dead.. and it can fail either closed or open, blowing the fuse or not... but with daemon.g i can actually monitor it and take action. thank you guys so much!
as an aside... the mosquito is really really really efficient even without a fan. my heat brake has a clog in it, and i followed this procedure https://forum.prusaprinters.org/forum/original-prusa-i3-mk3s-mk3-user-mods-octoprint-enclosures-nozzles-.../mosquito-clearing-a-heat-creep-jam-easily/, trying to melt the clog in the tube... i totally removed the mosquito from my hot end mount so nothing was blowing on it and using the duet control i set the temp at 270... it heated up and maintained temp without a thermal runaway for a good 5 minutes. by then the heat sink was too hot to touch... but there was no thermal runaway... it stayed at 270.. and also did not melt the clog.... either way....