Multi store problem. please help

Please help me.
i have multistore opencart setup like this:
1 http://domain1.com/store/ - main store
2 http://www.domain2.com/store/ - second store.

I also have Multi-domain ssl installed for:
http://domain1.com
http://www.domain1.com
http://www.domain2.com

and i have a redirect setup for with and without www domain1.com to go to http://domain1.com/store

Everything was working seamless from October 2015 till now. I had to renew my multidomain ssl. Hostgator reinstalled it, and it turned into a disaster. first they redirected my domain2.com to domain1.com, when i contacted them telling it should be showing a different looking website, they decided to remove the addon domain2.com from hosting and suggested me to forward it from domain account to domain1.com, then third person did some magic and managed to set up domain2.com almost back to its original condition (wasn't showing some icons, but was at least showing the correct site), and a week later, when i didnt touch anything, and i am sure they are also didnt touch anything, my domain2.com out of a blue begun to show internal error 500. To be more specific this is whats going on now:
1. http://www.domain2.com redirects to http://domain1.com/store/
2. http://domain2.com redirects to http://www.domain2.com/store/ and shows internal error 500 at the arrival.

and this is what should be going on: http://domain2.com and http://www.domain2.com should go to http://www.domain2.com/store/ (and there i should see the actual second store, while i see error 500.)

I need an advise on how to fix this, considering that:
1. the domain2.com is setup as an addon domain pointing to /public_html of main domain1.com
2. the opencart setup shows the second store as http://www.domain2.com/store/ and with ssl https://www.domain2.com/store/

What else am i missing here to make it work again? thanks.

A 500 error is an internal server error. If it worked before and now it fails, something changed. You should ask your host to check the server logs and see what the error is and they should help you.

Without knowing what that error is, there's nothing anyone can do.

the thing that has changed is they upgraded cpanel from 11.54.0.20 -> 11.54.0.21, but they assure that this cant be a problem. any confirmation that multi store works on cp 11.54.0.21?

Even if it does work, that won't solve your problem--it sounds like there is a specific issue with your site. The only way to know is to get that error message from the server logs.

Hi lovenatural,

Sounds like you need a new hosting company... If you do check here

Now for your issue you are going to have to basically go over the installation steps again to return your site to normal - http://forum.opencart.com/viewtopic.php?t=27538

More Helpful Information:

API problems - What you need to know
Moving Your OpenCart Store to Another Server

BTW: SSL should be for the whole domain not singular to any particular store on that domain.

Thank you Randem for your input. But like i explained, the setup you referred me, was working for 6 months seamless, and it doesnt now. and the only difference between then and now is upgraded cpanel by hosting. What i am trying to figure out is what could cause the issue and what steps i can take to troubleshoot this.

Since they upgraded your cPanel that could cause issues because you can do redirection in cPanel with sub-domains and in the upgrade yours probably got changed or deleted. there are a few things you can do

• Contact your hosting company to see if they will fix it
  
  Go into CPanel and attempt to redirect yourself. there are two places in Cpanel you can do this.
  
  • One you can change the DNS Zone File A (Host) @ record to point to the IP (main domain) that you want.
  • The other way is only in some cPanels where you can change the redirection of a sub-domain which will amount to the same thing but is more user friendly.

To see what is going on, open a command prompt and ping each domain or sub-domain and record the IP addresses. The way you need it to work is to have all the domains (sub-domains ) return the exact same IP addresses for your multi-store store to work correctly.