Take it out and have a look. I went to a Bosch oven where the customer was replacing a fan element (quote “because it’s an easy job”) had managed to catch a wire on the back panel. When he eventually got the element out, ee only saw two wires and replaced the two wires. Live wire was still touching the back panel…. the rest is obvious, big bang, then CU tripped. In this case it blew the t/stat. Some customers really should not be touching anything electrical. !!!