BACK UP: All of your ROMs/Homebrews & SAV files
Use
SD Association Formatter 3.0 (formerly known as Panasonic SD Formatter) to format your microSD. Be careful that you format the correct drive.
The default format settings should be fine regardless of what microSD card it is.
After format, decompress the latest AKAIO which is currently
AKAIO 1.6 RC2. You may have to download
WinRAR from RARLAB in order to "unzip" this archive. Copy the contents of the archive to the freshly formatted MicroSD. After this the contents of your MicroSD will be:
Folder - __aio
File - ak4menu.nds
File - LoaderChangelog.txt
File - readme_AKAIO.txt
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You can delete the two .txt files (they look like text documents, and your system may not be configured to show the .txt file extension once they're extracted).
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You can then restore your backed up ROMs/Homebrew & SAV files to the MicroSD. Make sure all the .SAV files are in the same directory as the corresponding ROM. You can copy all of them to root (topmost directory) or organize them in folders if you wish.
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Hope this helps. Please do not skip the backing up part. Last time I gave advice to someone about this kind of thing he formatted before backing up despite my advice to do the opposite and it was very funnysad.