[minecraft error with 1.8 forge makes the game refuse to even open]

i need help i downloaded 1.8 reccomended version with the too much TNT mod and my game is refusing to finish downloading!

this happens:

Failed to download file, the file contents differ from what was expected.
Name: netty-all-4.0.15.Final.jar
URL: https://libraries.minecraft.net/io/netty/netty-all/4.0.15.Final/netty-all-4.0.15.Final.jar
Filename on disk: netty-all-4.0.15.Final.jar
Path: C:\Users\Admin\AppData\Roaming\.minecraft\libraries\io\netty\netty-all\4.0.15.Final\netty-all-4.0.15.Final.jar
Exists: File

please help!