Consider that the heating element in the oven is defective- an easy conclusion to reach...
How do you fix it?
Remove the element and test it - if defective buy a replacement element and fit it.
https://www.youtube.com/watch?v=iOZZo8P1z9M
https://www.youtube.com/watch?v=5FhZYW-8XSI
Good Luck..., April 2017