You have already installed Pancake!
You almost certainly don't want to overwrite all the data you had.
If you are just updating your Pancake's files manually, you should find the file that was in
system/pancake/config/database.php before the update, and put it back there.
You cannot use the installer because you've already installed Pancake.
If you have any difficulty installing Pancake, don't forget:
We can install Pancake for you, for free.
Just
start a
free support ticket.