Issue started when heater relay burned up. Replaced relay, thermal cut-off, high-limit thermostat. Then heater stayed on with all settings. Replaced thermal fuse (it opened), thermistor, temp switch, and lastly, the control board. Then dryer would not remain running when start is released. Tested relays. Re-installed old control board. Start now works -and heat is always on. Are both boards bad?

Dryers