Can't start installer, 64bit, invalid magic number?

Must load kernel first.... OK, how? All boot options throw this error

Hey, welcome to the forum!

"Invalid magic number" IIRC means the file system is corrupt.

Is it a good USB/DVD? Is your iso's checksum correct? Try reflashing the ISO.

The reason it says "you need to load the kernel first" is because it tries to load the kenel, can't, but becauuse of the way grub handles commands, it still tries to boot the rest of the system. When it does, teh kernel still isn't loaded.