new R4 not working *Need Help* long term user unknown problem

New R4 --statement on card says SUPER CARD R4 Revolution 3 for dsCould not get card to load keeps stating LOADING and doing nothing else....soI have another R4 which works fine, so I swapped SD's no change in new R4 SD worked fine in old R4.
so to test the R4 i loaded the old one without its SD..it stated "Couldn't find the SD/TF card" so I tried this to the new R4 and it still only goes to Loading and does nothing else.......HELP is my new R4 gubbed!!!!

It's likely that it's fake, since you used other MicroSDs. Unless your MicroSDs are old, and one needs formatting, or one just can't be read.