ActualPepperoni

As title states, I cant get this to boot. Ive got two pi 3 B+, 3 of the exact same sd card as shown in the shop, multiple power sources. Ive booted raspbian on all the hardware stated previously. But for some reason mygmrs will not boot, at all. Ive wrote the image with win32 disk imager, pi imager, etcher, you name it. Zeroed the sd cards, ive tried everything. I would greatly appreciate if someone could take some time to help me out here...