Having a Series of Issues after Upgrading to 2.x

Greetings!
I'm experiencing a series of issues after upgrading to 2.x. You can test the issues here.

1. MiniCart missing in the header. The module is enabled.

Category page:
1. "Add To Cart" buttons don't work. I noticed a series of errors in the Console, but I'm not sure how to fix them (I know jQuery is defined as it is loaded when I view the source code):

ReferenceError: jQuery is not defined
[Learn More]
common.js:47:1
<anonymous>
https://courtscandies.com/furl/componen ... on.js:47:1

TypeError: jQuery.totalStorage is not a function
[Learn More]
toffee.html:428:8
<anonymous>
https://courtscandies.com/furl/toffee.html:428:8

Product page
1. Images, when clicked, do not pop up (they used to).

---aside from the above errors in the Console---

Loading failed for the <script> with source “https://courtscandies.com/furl/componen ... pup.min.js”.
32-toffee.html:47

Loading failed for the <script> with source “https://courtscandies.com/furl/componen ... /moment.js”.
32-toffee.html:48

Loading failed for the <script> with source “https://courtscandies.com/furl/componen ... ker.min.js”.

TypeError: jQuery(...).tabs is not a function
[Learn More]
32-toffee.html:424:1
<anonymous>

TypeError: jQuery(...).colorbox is not a function
[Learn More]
32-toffee.html:332:2
<anonymous>
https://courtscandies.com/furl/toffee/p ... html:332:2
i
https://courtscandies.com/furl/media/ju ... js:2:27444
fireWith
https://courtscandies.com/furl/media/ju ... js:2:28213
ready
https://courtscandies.com/furl/media/ju ... js:2:30004
K
https://courtscandies.com/furl/media/ju ... js:2:30366


Shopping Cart Page:
1. Dropdown accordion does not work. Clicking it leads to a different page.

2. The 'Remove' button in the Shopping Cart doesn't work.

Checkout page:
1. Accordion doesn't work, and I cannot test the rest of the checkout to verify this actually works.

I'd appreciate a little education on why this isn't working.

Thank you.

You obviously decided to keep your extensions installed during the upgrade which should never been the case. When upgrading the database, always uninstall all extensions first whether it is delivered from the core or as a 3rd party extension. In addition, always ensure that each extensions you have previously installed before upgrading are compatible with the new release of Opencart you are launching the upgrade from.

Restoring backups would be the best course of action. You may also seek for professional assistance to complete the upgrade process.

You obviously decided to keep your extensions installed during the upgrade which should never been the case. When upgrading the database, always uninstall all extensions first whether it is delivered from the core or as a 3rd party extension.

That is because I'm not familiar with how to upgrade the OpenCart. Instead I followed instructions elsewhere and this is where it got me. So would the best alternative is to restore the old site, remove all of the extensions, then upgrade?

That is because I'm not familiar with how to upgrade the OpenCart. Instead I followed instructions elsewhere and this is where it got me. So would the best alternative is to restore the old site, remove all of the extensions, then do a backup of my whole store and database, then upgrade?

Yes, this would be the best route to go if you want to do this on your own.