I really don't know what the problem is here. Grub2 has nothing to do with whether an ISO will boot or or not - it is up to the system itself and the hardware it is aimed at. If the system has been built properly and the hardware it is to be installed on is set up properly, then there shouldn't be an issue. i'm no fan of Grub2 but I've never been able to blame it for a failed install. Currently the testing version of VillageBox is sitting on a usb stick. Has been for the last couple of remasters. I can update, fiddle about and remaster off that stick - no problems. It was installed off another stick that was "dd'ed" off the computer. VillageBox runs Grub2 - yes, it's a complete PITA to configure, but it's not why things don't work.
The fallback method is to burn to a cd and try booting from that. If that works then the system itself is fine - Grub2 included - and the problem lies somewhere else. Unetbootin is often used to "burn" a usb stick, but that is usually because the ISO does not have syslinux installed. Remastersys does, so any remaster from that stable simply needs a "dd" command to put it on a usb stick. I have over half a dozen USB sticks - three are dedicated to "dd"; they are new and specifically for the task - I don't trust the others and for good reason. That is the nature of flash drives.
As an aside, why anyone would go to Windows to set up a bootable Linux system is beyond me. I have never had Windows on a computer - never had to, never intend to. Windows to me doesn't exist. So why use a system which is the antithesis of Linux to install Linux to a device? Yes, at times I've had to reformat USB sticks through a Windows machine because we live in a small town and that was all we could get. Caught out on the hop trying live-ISOs! Have since bought other non-compromised sticks!!
Anyway, not that this is helping anyone's problems, other than to say that the obvious isn't always, and always check the hardware - and don't trust flash drives!
Sorry - I think I got stuck in rant-mode! Gotta do something about that.