Do you already have a to dump your files?
To ensure you have the correct, unmodified files, it's sometimes helpful to compare the MD5 checksums of your dumped files against known-good values. For example, the correct MD5 for the standard bios7.bin file is df692a80a5b1bc90728bc3dfc76cd948 . dsi bios7.bin
: Use a homebrew application like DSiidumper or DumpTool . Do you already have a to dump your files