hotstart uploaded but I get a 404 error

Oh ! sorry.
I forgot to say :

1/ It's a 500 error not a 404
2/ I've copy whole hot_start zip file and then unpack it on my server using my hosting control panel.

OK. I found what was wrong.

In your instructions you say to put 777 rights on the folder. Here is the bug.
When I give 777 rights, Server error. When I let 755 it works.