You must store an MD5 hash in your serendipity_authors table. So if you choose the password "jackal" you would need to store "5da520440785b95df2c6016087c315ae" in the database, but when you login, still use the password "jackal".
You cannot login with the MD5 hash itself.
I have mmigrate my blog. Actually I have just upload a new database because then I have used a fresh installation.
I know it is was not the best thing to do, but because I wasn't able to manually configure the site, I decide to reinstal it, provideding the info of the updated database.
Everything went fine and the standard appareance was online showing my post.
Unfortunatelly, Now, I am not able to access to the admin area.
I try the methowd Garvin shows here, but even with that it doesn't work.