Colin O'Flynn started the ChipWhisperer project to bring power analysis & fault injection tooling to everyone, and also co-authored the Hardware Hacking Handbook.
You probably wouldn't consider power analysis & fault injection being a required skill set for your oven repair person. But when your oven is actively lying to you and not just broken, a new type of repair is needed beyond just replacing a heating element. This talk starts from a common complaint: how a range of Samsung ovens show you only the set temperature, and the actual temperature varies widely (and is often incorrect). Using an attack combining power analysis & fault injection the code protection of the Toshiba TMP91FW series microcontrollers used in the controller is bypassed using a ChipWhisperer-Husky, which allows recovery of the oven firmware. From there the firmware is reverse engineered, and new functions are added to output the internal measured temperatures & control signals for analysis. This allows us to definitely demonstrate that the reason our thanksgiving turkey took so long to cook: an inflexible control system that cannot enable the heater long enough. Finally as a proof of concept, a patched version of the firmware improves how quickly it can recover, and is demonstrated cooking a souffle (all while displaying the actual oven temperature, also fixing one of the other common complaints). The documentation and tools are helpful for others repairing these ovens, hopefully diverting them from become waste.