Overheating protection reset for R1 heater
The symbol for heating (small bubbles) should be visible if the target temperature has not been reached. In the video it is visible and that means power must flow to the heater's protection thermostats.
The red indicator light on the heater will then light up indicating that the heater is working.
If it doesn't, the problem is likely that the overheating protection has tripped. It can be reset via the "rubber button" located in the center of the black protective cover. When resetting it is important to press straight down. If you press from the side and obliquely, the pin under the rubber button can come out of position.
If that has happened, then the plastic cover must be opened, FIRST DISCONNECT THE POWER, and this is done by loosening the screw at each end of the protective cover. When it is swung down, the brown reset button is visible, which can be pressed down with a chisel or similar. A "click" is then heard, which indicates that the protection has been reset.
The heater is located above the circulation pump for the models below.
MEDIO: Pump and heater are in the corner between sides 2 and 3.
DOPPIO: Pump and heater are on side 3
EXELL: Pump and heater are in the corner between sides 2 and 3.