What .exe are you talking about? It's an archive (.rar) that you unpack to an empty folder and run InsydeFlash.exe. The computer will reboot or shut down after the bios update is finished.
I've followed the instructions and when I try to boot up, it says BOOTMGR is missing, Press Ctrl+Alt+Del to restart. I've used the files provided in the other topic and it doesn't work. Why? And I couldn't really select the option to use DOS files. It is greyed out but I used Windows Enabler to force it to be ticked.