If you are looking to flash your Nokia 5800 using RPKG files or raw firmware, proceed with caution. Symbian flashing is not as forgiving as modern Android flashing.
The Nokia 5800 XpressMusic is a Symbian S60 5th Edition smartphone (released 2008). An RPKG (Rom Package) is a firmware image file format used for the 5800 and related Nokia devices containing the device ROM filesystem and applications. This study covers what an RPKG is, how it’s structured, why it matters, typical workflows (extract/modify/flash), risks, tools, and illustrative examples. nokia 5800 rom rpkg