One burner (left front) heats up too much. You cannot regulate the temp. Everything heated on this one element burns.

Based on your question that the right front burner of your Schott Ceran glass cooktop is not working, here are some steps you can try to troubleshoot the issue:

1. Check the power supply: Make sure that the cooktop is properly connected to a power source and that the circuit breaker or fuse is not tripped. If the circuit breaker is tripped, reset it and try turning on the burner again.
2. Check the burner control switch: The burner control switch regulates the power to the burner. Check if the switch is loose, damaged, or defective. You can test the switch for continuity with a multimeter to determine if it is functioning properly.
3. Check the heating element: If the burner control switch is not the problem, the issue may be with the heating element. Check the element for visible damage, such as cracks, burn marks, or discoloration. If you see any damage, the element may need to be replaced.
4. Check the wiring: Check the wiring connections between the burner control switch and the heating element. If any of the connections are loose or damaged, this may be causing the issue.
5. Test with a different burner: If you have multiple burners on your cooktop, try testing the right front burner with a different control switch or heating element to determine if the issue is with the burner or another component.

The above are basic means of troubleshooting, the following below will add more to the solution above;

Check the control board: The control board is responsible for sending power to the heating elements. Check the control board for any signs of damage or burning, and test it for continuity using a multimeter.

Check the thermal fuse: The thermal fuse is a safety device that cuts off power to the heating elements if they overheat. Check the thermal fuse with a multimeter to see if it has blown. If it has, you will need to replace it.

Check the switch relay: The switch relay is another component that can cause the burner to not work. Check the switch relay for any signs of damage, and test it with a multimeter to see if it is functioning properly.

Test the voltage supply: Use a multimeter to test the voltage supply to the burner. If there is no voltage, this could indicate a problem with the control board, thermal fuse, or switch relay.

Check for loose connections: Inspect all wiring connections between the control board, switch relay, and heating element. Loose or damaged connections can cause the burner to not work.

could be either, but usually it is the element

SEE PICS Or Oven safety valve needs to be checked with multi meter ohms / voltage
ALSO Test the Burner Heating Element
The stove's burner heating element is a coil of metal sheathed in an insulator. Electrical current travels through the element. Resistance to the passing of electrical current causes the element to heat up. A precise temperature cannot be set for a burner, instead it is turned on and off repeatedly by the control to the achieve an average temperature. When it is set to a low temperature, the element is cycled on and off more frequently. For high temperatures, the heating element is energized longer with fewer on and off cycles. Some burners have two elements, with the second only being used only for high heat settings.
Before testing the heating element, unplug the appliance or shut off the power at the fusebox orbreaker panel to avoid an electrical shock hazard.
When a burner does not heat at all, or only heats up to a lower than expected temperature, the problem is likely to be with the heating element, the temperature control switch, or the wiring. If it only heats at the highest temperature, the problem is with the control or an electrical short, not the burner. If the burner works only intermittently, the problem is likely in the wiring or connectors. To test the heating element, try the following steps.
First, disconnect the heating element from the stovetop. In most cases, this is done by lifting up the burner on the side opposite of the terminals (the part of the burner that disappears under the stovetop). Remove the decorative ring.
Inspect the style of connection. If the burner element has visible blades that fit into the receptacle block, pinch the block with one hand, and pull the heating element free with your other hand. If the terminal block clamps over the element, the housing must be removed and the burner wires disconnected. Unsnap the metal piece or remove the screw that secures the receptacle block and then disconnect the element.
Inspect the heating element. If you find bubbles, warping, or damage to the insulation sheath, the burner must be replaced. If the terminals are dirty or corroded, this can cause poor temperature control, intermittent problems or complete failure to heat. Clean the terminals with steel wool or very fine sand paper to restore good conductivity. Test the resistance of the heating element using a multi meter. Set the multi meter to the ohms setting X1 and touch one probe to each of the terminals. A normal reading is typically somewhere between 20 and 120 ohms. The exact reading differs by manufacturer and mode. If the meter reads infinite resistance or the other extreme of the scale, zero resistance, then the element is damaged and should be replaced. If the measured resistance differs significantly from the expected range, the element is probably bad, but if possible, determine from the manufacturer what the actual resistance should be.
To test for a grounded or shorted element, touch one probe to the surface of the burner and the other probe to each terminal in turn. If you get continui

Sounds like the heating/starter element went out. This item is very delicate and will break if touched. They are used on almost all newer gas appliances. It takes about 3 minutes to check. Turn the oven on and look down near the burners with all of the lights in the room out. You should see a glow for a while, then it will click off for a while and then come back on. If not, then turn off the oven and get a flashlight and look for the starter element to see if it is broken. It is about one inch wide, two inches long, and 1/4 inch thick. If you do get a glow then this is good news, the element is not broken. However, the element operates a thermostatic switch which operates the gas valve. This switch may be broken. The switch and the starter element usually come out together when removed.

You may already be aware of this but ... If our ilve ceran cooktop is the same as yours turn the knob past the 12 setting till you feel pressure and it springs back. This is the switch to fire up the marked outer elements.

Bad control or infinite switch. replace the switch for that element and you will be good to go.

Your referring to an electric range I'm assuming. In that case the heating element is only heating to a mid-point then stopping. This typically means the heating element is burnt or is partially burned out. The element is usually user replaceable and requires the old one be unpluggude and replaced with a new one. You'll need to get the element from the manufacturer.

I suspect a faulty element or electrical connection to the element.

yes it is your control infinite switch the knob swicht that goes from 1 to 10 or min to max thanks from gilles

these are cartridge elements corrrect? try reversing the cartidges, now the front small will become the rear small . does it not work in this position? and the newly placed front burner work?? this will determine if the proble lies within the cartridge or the switches