Electrical Engineer for Appliance Retrofit

We need an electrical engineer / embedded systems engineer to help evaluate and prototype a control retrofit for an existing appliance. Goal: determine if the machine can be safely controlled through its existing button/control inputs using an Arduino or similar controller. We are not looking for a full appliance redesign, firmware rewrite, or custom PCB at this stage. Concept: * Payment reader such as Nayax approves payment * Payment reader sends relay/pulse to Arduino/controller * Controller unlocks Start on touchscreen/HMI * User presses Start * Controller checks door sensor * Controller electronically mimics button presses on the existing machine * Controller runs shortened cycle: 3 min steam, stop, then 2 min dry, stop * Touchscreen shows countdown, paused, and complete messages Need help with: * Mapping existing control board * Identifying safe low-voltage control points * Recommending relay vs optocoupler method * Confirming Arduino can trigger Power / Cycle / Start-Stop * Adding independent door sensor for pause/resume * Keeping factory safety systems intact * Creating wiring diagram, parts list, and prototype plan Important: do not bypass heater, fan, pump, mains wiring, thermal protection, low-water safety, or door safety. First milestone is feasibility review and go/no-go recommendation. If feasible, we can continue into prototype build.