It probably caught fire because to much crud was built up inside probably from not cleaning often enough. I assume there were not flames but just a lot of smoke, try again but watch it carefully. Some ovens are damaged by oven cleaner so I would get a manual first to be sure using that would be OM.
When the food you're baking is done on top but not on the bottom--or when baking just takes far too long to finish--the bake element may be burned out.
You may get fooled into thinking it's working, because the oven is hot inside. But many electric ovens use the broil element, too, during the preheat and bake cycles. So the food may be getting heated only by the broil element, which causes poor baking results.
If the bake element is burned out, replacing it should solve the problem. Otherwise, you need to further troubleshoot the oven's electrical system to locate the defective wire or component.
on the oven's smooth surface you should use a razor blade and scrap off the plastic (when cooled).. if the plastic melted on the burner, you may need to replace that particular element from a local appliance part store. easy to do.
When foods are burned, soggy, or baked unevenly, it generally means heat isn't being distributed evenly throughout the oven, its escaping out the door or the controls are out of adjustment.
1) Remove any aluminum foil from racks or the bottom of the oven.
2) Check the door gasket and, if necessary, have it replaced.
3) Be sure nothing is obstructing the vent.
4) Reposition the oven racks so baking pans aren't too close to the heat sources.
5) Check your baking pans. If they're dark, they may be burning your food. Reduce temperature by 25 degrees F when baking in dark metal or glass pans.
6) Recalibrate the controls.