Recover saves from corrupted DB

Hi,

Yesterday I got a power surge while booting my PS4 5.05 now it is stuck when rebuilding the database.
And the only way to fix it seems to do a clean install.

If I switch the hard drive is there any chance that I can put the original hard drive as USB external storage and get the save data using FTP or something else ?
Or am I doomed and lost all my saves ...