wp-admin blank page and weird view-source code

Question

I have a website that is now missing wp-admin page. It is blank, even the page source code displays (sorry its long)

<div style="display:none;">rest of code</div>

Here is the pastbin link to the code - stackoverflow flags it as spam.

Is there any way to find out what is causing this (i assume malware) and where to locate the issue?

I've renamed themes and plugins folders and the wp-admin is still blank.