Repair the sketch to work DFPlayer c Arduino

Development of an MVP online tutoring platform (analogous to Preply) for the Lithuanian marketProject description:We are looking for a team of developers or individual specialists (Full-stack / Backend / Frontend / UI-UX) to create a two-sided online learning marketplace for the Lithuanian market.The goal of the project is to launch a web platform that connects students with freelance tutors for conducting individual lessons in real time.Main functionality of the MVP: Tutor's cabinet: Profile with a video introduction, upload of diplomas, schedule setup (calendar) and hourly rates. Student's cabinet: Search by filters (subject, price, language, rating), purchase of lessons, personal class calendar. Search and filtering: Smart matching of teachers with a review and rating system. Virtual classroom: Integration of video communication (WebRTC, Zoom or similar), built-in chat and file sharing. Payment system: Secure transaction (Escrow). Freezing of funds and payment to the freelancer after lesson confirmation. Integration with Stripe / Paysera is needed.

Good day It is necessary to create a module that will work with the Firebird database in C++ for selling products. There are examples of ready-made solutions and a description of the module's functionality. Main functions: authorization, selection of products on the screen from groups/subgroups, transition to the cart, payment by card, and printing the receipt. The program must work on Windows 10 and above, using the existing database.

Write and create a mobile application. A creative and highly professional approach is needed, as the idea of the application is not ordinary)