Windows 10 theme stuck on grey screen

I was downloading and testing themes from deviantart, and I saw a neat one. Long story short after applying it to my windows 10 it is stuck on a grey screen. The UEFI hotkey is not working and the grey screen will not let me do nothing at all therefore cannot access UEFI from normal means. IThe only idea to mind is to put the HDD in another pc and boot elsewhere. Erase the theme and hope for the best.

It was my fault, I didnt read lower in the description were it said to not use it with windows 10 10240 and above. Now I lost complete access to my laptop. Any ideas would be appreciated. Before I go screwing any further.
 
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