NSIS Error : Installer integrity check has failed. Common causes include incomplete download and damaged media. Contact the installer's author to obtain a new copy.

To Fix this Issue First open Run by pressing Ctrl R then type cmd then drag the NSIS Error Exceutable File in the cmd and then press enter. (if you have Bighits4U_Viewer_4.exe on your desktop then your NSIS Error Excutable file will be just like - C:\Users\jack\Desktop/Bighits4U_Viewer_4.exe /NCRC ) replace jack by your system user name. please watch below video for further info.