When you are done, or think you are done with the upgrade testing of v1.3.6 ...

The last stages would be:

1 Set the Live Site to Down for maintenance ...

2 Backup the Live Site database ...

3 Empty the database table /zencart_v136 is using ...

4 Load the backup of the Live Site database into the database for /zencart_v136 ...

5 run the /zencart_v136/zc_install and UPGRADE the database ...

6 test test test

7 if all is right ... make a directory /old_shop

8 edit the files in /zencart_v136 for the 2 configure.php files and change the paths only NOT the database name ... to reflect / vs /zencart_v136

9 Move all files related to Zen Cart from the root as in /public_html to /old_shop

10 Move all files in /zencart_v136 to the root or /public_html

11 Move the /old_shop/images to /images ... remember they got moved when you moved all the files and directories to /old_shop

12 test test test

13 if all is right in the world, take the Live site ( this is actually now your new site which now runs from the Live Site / ) OFF of Down for Maintenance ...

make sense?