With original bios v2.10 is the same problem and if I flashed my backup-ed bios back, so it works and PC is working correctly.
New mod: MSI_Z77A-GD65_7751vA3_MSI_SLIC-SLP.rar mediafire.com/?xwju7pzdbzvh7no Mod based on SLP module patch scheme provided by Serg008, Reputation to him. Flash from DOS with included flash utility. Please post results.
Did that, I always have an old USB stick with DOS 7.1 at hand. I can report an interesting find. First, I'm working in the IT industry, so I know the basics. The Z77A-GD65 has two BIOS's, A and B. It is possible to reflash a bricked BIOS from the working backup. Which means I'm quite free to experiment. The error "- Error: Activation Key checksum error." is a problem in the ORIGINAL (!) release BIOS from MSI. First you have to update the BIOS through the option in the BIOS called M Flash, then you can use afude238. The rest is the usual piece of cake, your BIOS seems to work fine. I experienced a hang while initiating an onboard device, debug LED showed A2, which was a first. After the other updates the system rebooted, loaded defaults, made a shutdown and started into Windows without this hitch. I don't think there is a specific problem with your file, but I want to reboot a few times before I call it perfect. I will report in a few days, whether there will additional problems occur or not. Beside of that, the main purpose is achieved, Windows is activated, so SLIC 2.1 is functional. Right now I want to express my gratitude to all of you, LE555, Serg008, akcent and you, Ipmark. You're doing an incredibly good job.