I upgraded from 1.3.9 to 1.5.0 using Fantastico, and everything looked fine

Except that I got a warning that the SQL Database patch level was still at 1.3.8.

I had no zc_install folder, so copied it over from my computer to the server. Now, I can't access my store at all - 500 Internal Server Error

I didn't run it - I just copied it! I do see now that it was zc_install from 1.5.1. instead of 1.5.0

Should I attempt a restore back to to 1.3.9 via the Fantastico backups?

Or is there a thread which will walk me through this (I also did the backups recommended in "3 Easy Steps to Upgrade Zen Cart")

I thought I did my homework, but now I see that the Fantastico option is considered to be a bad idea.

Now I am afraid to make a move without expert advice.

Also - my skill level at this could be considered marginal