I'm going to humbly suggest that you are doing what many of us did on first arrival to the Zen Cart family.
"I'm a ##########___ (fill in here Developer, Programmer, Designer, Etc), I can just jump in here with both feet and get this done."
Several will agree with me that this only leads to :frusty:
Your are upset with the instructions yet you seem to be jumping around doing things that, unfortunately, are just making matters worse. Been there, done that.
You've got to go step by step and make some starting decisions based on the fact that you are using 1.3.8. It's VERY old and hackable. Most mods that worked in 1.38 will NOT work in 1.5.3. You will need to decide which ones you really need for 1.5.3 and determine their currency. If not available, you will have to make something else work or just drop the mod. That's step a) of http://www.zen-cart.com/entry.php?3-How-do-I-rebuild-my-site-on-the-new-version-instead-of-upgrading rebuild method which is, IMHO, your best bet.
Here's what I would do in your case.
Load a copy of the latest hotfix zip to your site's root.
Create a new database for the rebuild. ZC will populate it for you during installation. NOTE: the new database prefix should match any prefix in the old database.
Extract the hotfix zip to the root and rename that directory to test.
Run yoursite.com/test/zc_install to zencart and populate the database.
DO NOT drop the zc_install directory or rename the admin just yet.
If not already done, I would go to the admin of the 1.3.8 and set it Down for Maintenance.
Delete the tables from the 1.5.3 database and insert the tables from the 1.3.8 database.
Run yoursite.com/test/zc_install and select update the database. It will ask for the admin password. That is the admin from the 1.3.8 database that you inserted.
When done, you may see some skip or ignore notices. They can be ignored.
NOW you can delete the zc_install directory and rename the admin to something of your choosing.
NOTE: Never during any of this did I mention either configure.php file. They are designed to be created and take care of themselves during installation!
The only things you will need from your old installation are the define_page files and images (product, etc) from the old site.
At this point, you have an ugly, operational cart that has no shipping or payment modules. Put the shipping and paying in place and start thinking about a mods. Zen Cart is browser/search engine ready out of the box so, for speed in getting back to work, use the minimum mods. You just have to have to make it work your way.
Next, get rid of the ugly. A new template is in order. With today's tablets and smart phones, look at something that's responsive. It will give you a step up on the competition.
When you are happy with the basic operation/look of the site, head back to your site's file manager and compress the root directory into a zip (don't include the test directory). Essentially this is a backup just in case it's needed. Delete all the old 1.3.8 files and copy the files in the test directory to the root. NOW YOU ARE GOING TO NEED TO CHANGE BOTH CONFIG FILES UNDER THE ROOT TO REMOVE THE /test REFERENCE. About four to five places in each one.
You now have two working 1.5.3 ZC shops pointing to the same database. If you want to continue using the /test directory for development, copy the 1.5.3 database to another (use the same username and password) and put the name of the new database in the two configure.php files inside the /test directory. You now have an operational shop in the root and a operational test site in /test. Time to PLAY!
Most of this can be done in less time than it took me to type it. AND... I would not have done so had you not mentioned your qualifications. I would not avoid the steps in the link above for most folks. I believe you're going to have those "I can do this" moments that get you in trouble.
EXTRA NOTE: Can't think of a single time that ZC has caused a 500 error. Those are problems on the server.
No one has brought this up yet, BUT, since you are running 1.3.8....Is your server ready for 1.5.3? http://www.zen-cart.com/content.php?48-what-are-the-server-requirements-to-run-zen-cart
Hang in there, try not to read into things, stay on track and let us know when you have a question.:yes:
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