Moodle 4.1→5.1 Migration & Theme

I need all site settings, user data, and course content moved from my current Moodle 4.1.2 instance into a fresh 5.1.1 installation that is already standing by on a new server. The existing site hosts course materials, quizzes & exams in the form of videos and h5p questions.

Beyond the core migration, I also run a Edwiser RemiUI theme with blocks and H5P activities. The theme must be upgraded or refactored to a new fully supported free theme like boost union so it renders flawlessly under Moodle 5.1.1 and will not come with additional costs or software lock-ins. H5P content should continue to play as it does now; if a newer compatible version is required, please handle that in the process.

Deliverables:
• Complete backup-and-restore of the 4.1.2 database and moodledata into the clean 5.1.1 site
• Verification that all courses, users, grades, quizzes, and multimedia function correctly
• Free new theme installed, configured, and documented, inc uploading courses into theme for Moodle 5.x
• Confirmation that every H5P activity loads and reports scores normally
• A short post-migration report outlining steps taken and any residual tasks I should monitor
• No php or other errors