Heater/ Thermistor - wiring
Once you just successfully checked that both of your fans are spinning. Your printer is just automatically checking that your Hotend Heater/ Thermistor is plugged in properly.
What to do when the error occurs
The most common source of the error is misplacing your Heater - Thermistor position on the miniRAMBO board. So please double check your MK2/MK2S Electronics Wiring.
If you do not find anything wrong with the Electronics assembly. Then, even though it is unlikely that one of these came damaged, we must check that your Heater/ Thermistor is working properly.
How to find out if your Heater or Thermistor is defective?
The best and easiest way is to take hair dryer and blow hot air at the Nozzle/Heatbed. During this process just check if there is any temperature change at the LCD. If there is a change it means your thermistors are working. If there is no change at all, your thermistor is defective.
If you would still need our help, please contact firstname.lastname@example.org.