I've made a custom web template based on BLANKINTERNET that has a specified DefaultPageLayout and a set of available page layouts, these are set in the Publishing Feature. I upload the solution and install it thru PowerShell and then I go to New site thru Site Actions. I can choose my template and a name for the new site but when I create it I just get a 404. I can however reach the settings of my newly created site thru Manage Content and Structure and there I see that the page layouts are there so that works. Does anyone have an idea why I get a 404? I have put a default.aspx file in the same folder as ONET.xml and Elements.xml but I have had no luck so far.
Did u create a Module to provision the default.aspx page? This element can not be in the ONET.xml so you'll have to create a Feature for this to provision the actual page.
U can read this post on how to implement Web Templates the right way. It is the best information available in my opinion: