Hi,
If you're creating proper overrides when modifying your views, the "default copies" (meaning the original core files) always remain untouched in folders /components/com_hikashop/views/VIEW_TYPE/tmpl. They are only overwritten when you update HikaShop.
Your view overrides are located in subfolders of /templates/YOUR_TEMPLATE/html/com_hikashop. They are being created, and eventually altered, when you're modifying views with the respective interface in the HikaShop interface. They will never be overwritten by a HikaShop update. Which also means that HikaShop updates to view files will not make it into your overrides, of course - and that seems to be your case.
If you click the trash bin icon in HikaShop's interface, the override will effectively be deleted completely! So, before doing so, you may want to create a backup, either of your entire site (as you have probably done before updating software anyway), or at least of the mentioned folder containing your overrides.
Alternatively, and for testing purposes, you may as well rename individual override files or folders per FTP to "turn off" overrides temporarily.
So, why not trying this: rename the folder /templates/YOUR_TEMPLATE/html/com_hikashop to disable all your overrides, then reload the frontend and test?
Or as I said in my last post, switch to Protostar temporarily (which does not include your overrides), then reload frontend and test?
If it works without all of your overrides, you know the culprit is still in one of them. You can then narrow it down to the one causing it by re-enabling all your overrides (or switching back to your template), then renaming them one by one (focus on the ones in the "product" subfolder") until it works.