Doesn't look like a flat wall, it looks like steps, and there would be snow on them...
Suggestion: to make the wall look flat give it all the same color as in your source pic.

Maybe find a nice grime or grunge texture and overlay it to your wall also??

very good use of source

good work

love the perspective.. and the visual bounce back really keeps you locked in.. good work

Thanks for the comments. I have made some adjustments.

Good work, nice job here the front kinda looks like steps but I like what you've done good luck

Snow looks bit flat gl