My radio is locked out

Hello, I know you'll be frustrated by this, but you'll simply need to get guidance from either that dealership or another expert Mercedes repair facility. If there are tricks to the trade, these folks will know, and making a good relationship in person could be very beneficial to you. It is possible they may even give you easy advice without charge. Here are some repair facilities near you: https://repairpal.com/repair-shops/mercedes-benz-repair-and-service-in-humble-texas