The Windows 8.1 RT update has been removed from the Windows Store, with a resent post quoting:
“Windows RT 8.1. Microsoft is investigating a situation affecting a limited number of users updating their Windows RT devices to Windows RT 8.1.
As a result, we have temporarily removed the Windows RT 8.1 update from the Windows Store.
We are working to resolve the situation as quickly as possible and apologize for any inconvenience.
We will provide updates as they become available.”
To assist those whose devices are effectively BSOD (Blue Screen of Death) or effectively bricked can download an original image of the Surface RT, along with instructions included on how to use, can be found here http://www.microsoft.com/en-us/download/confirmation.aspx?id=40810