You can find the necessary files through community archives and enthusiast sites:
with Symbian Belle, you can use either the last official firmware or modern community-developed custom ROMs. Since official Nokia update servers are now offline, you must download firmware files from third-party archives and use specialized flashing tools. 1. Download Sources (Belle Firmware)
A modern project called Reborn is highly recommended for 2026. It is based on Belle but includes updated HTTPS certificates for modern web browsing, a working app store, and removed app-signing restrictions.