I don't think Cacko supports the 5500.
Read the pinned post above:
https://www.oesf.org/forums/index.php?showtopic=15820Cacko Rom 1.23 Is Released
Cacko ROM 1.23 is released. Supporting Zaurus models are: SL-C1000, SL-C3100 in addition to SL-C7x0/SL-C860.
Hope you have a backup, there are original backups available to download,
there are other methods to restore a Zaurus, but you'll have to search the forum for that. I only have used the backup, (which I downloaded), for my C3100.
Jon