i have no ideea about the implications but this is how i solved the problem with the fk. slider :
(you will lose all pictures. if you have to move it up a little use module = positions = Run Live Edit = and drag and drop it.)
1. i have deleted all default theme, (maybe you should delete only ..... module ... ) = with preferences = themes = delete
2. edited homeslider.php on cpanel this time and changed (edit) 779 to 1275 (whatever, easy and fast to find)
public_html/modules/homeslider/homeslider.php
3. hit "Reset" on the module in PrestaSHop. after that when you enter to configure you will have 1275 (whatever) and have to reinstall all pictures.
p.s. i will never use reset again with any module. maybe you should find a solution without deleting all the default theme. i think you can delete only slider module in default theme then modify the file. i can change everyting now but i have no default slider module. i need a guinea pig who will only modify the same file on default theme and in the one mentioned here and not delete anything. this guineapig is already dead.