Yes. They are all empty to my knowledge (I haven't actually tried them apart from 1)
All are unredeemed, just with no value.
How can they be unredeemed with no value??? The store didn't activate them???
I guess that could be a possible explanation.
The seller didn't specify where he got them from on the listing.
Re the valid/invalid point, I'm not sure what you mean.
These have no value. You can try redeeming them, but it'll probably not work as the codes have no value loaded. (Possibly because they weren't activated).
So they are basically just a novelty? Or is there a way to activate them and add value?