Customize function broken in Epik

I have an older site (accunect.com) that is running Epik 1.4.1 and for some reason when I click Appearance->Customize I get an error message:

accunect.com is currently unable to handle this request.
HTTP ERROR 500

I’ve updated WordPress and Genesis, no help.

I have Epik 1.5 running on other sites, and it works fine. I’m wondering if I upgrade accunect.com to 1.5 if it will fix the problem, or if there’s something other way to fix it.

I would actually like to upgrade to 1.5 so that I can more control over the theme color instead of just the presets – is it an easy process?

I have very few edits to my style.css, and my functions.php is still the same as original.

All of which makes me hope that upgrading to the newer version should be painless but I want to confirm that before I do, and to check to see if that will fix my customize problem. We have a newer version of the logo to use as a header image and I can’t easily replace it right now.

Thanks for your help.