Bosch Nexxt 500 Series won't heat up

Dryer will not heat up. Repairman came out last week (I have an extended warranty) and "reset" some switch (sorry - not at home, wife met the repairman). Said if it happened again, they would have to replace "it". It happened again. The repairman can’t make it out for 5 days and laundry backing up. Any idea what the switch he "reset" was and how to reset it myself (until they can replace it)?