Hello there,
It's legit to be frustrated after the misunderstanding, we completely understand that.
The fact is, Helix Ultimate 2.x.x is Joomla 4 compatible, we have already announced that. But the templates based on the framework are not compatible yet. You can even see it on our site here. Every template is tagged with the Joomla 3 compatibility.
Framework compatibility has nothing to do with the templates compatibility to be honest, I am sorry to say that.
I hope you have a full site backup of your site. If yes, pleass restore that to go back to the previous version.
If you want to build a complete fresh site, you can use Helix Ultimate 2.x.x and Joomla 4 as these two are compatible with each other. However, we highly recommend not to update to Joomla 4 or even Joomla 3.10 if you already have an existing site based on any other templates we have except Helix Ultimate.
I hope you can understand the fact.
Thanks!