The display LCD and digitiser are fused together, so if you had to replace the screen it would cost quite a considerable amount - that's if you first check the connectors. Tearing down the device is medium to hard difficulty, you will need to remove most of the components to get to the display.
In the age of saving money and time I would suggest returning it for a refund and try to find another on eBay or something (I recently got one for £300 on eBay).
In the age of iFixit, tear it down, check the connectors and factory reset the device once again.
Hope this helps!
Will