Legal Question in Intellectual Property in California

Although it's possible, I think it's unlikely that the trademark holder would attempt to enforce its trademark rights against small retail-size repair shops. When it comes to customization, however, I would expect Apple would take a more aggressive stance. Companies get defensive when outsiders attempt to customize or modify their products. You might try contacting a half dozen or so repair operations that seem similar to yours in size and scope, but that are not your competitors (i.e., are located in other states) to ask if they have ever been challenged, have they ever asked for permission or a license to advertise iPhone Repair, etc.