Whether you are experiencing boot loops, want to manually update to a newer build, or are trying to recover a bricked device, understanding is essential. This article covers everything: official update paths, finding the correct stock ROM, using the Nokia OST LA tool, and troubleshooting common firmware failures.
Because official support has ended, many enthusiasts use custom ROMs to keep the phone current: Nokia 6.1 Review - Exotic Security Firmware NOKIA 6.1