Neon tetras questions?

I could see some losses with the Neons just from adding 7 at a time. They are very sensitive to trace levels of Ammonia, and adding that many at once you probably had an Ammonia spike. Daily partial water changes would be a good idea. They also might be having trouble if your tank has been set up for less than 6 months, they are sensitive and need established tanks. If they were shipped for a while, the stress from that could also be a factor. If you didn't drip acclimate, they could also be having trouble if your water is very different from the water at Big Als.

Neon Tetra disease is rare. Most of the time people think that might be the problem but it's actually something else. It's caused by a parasite, so it's pretty hard to dodge. They either carry it or don't. Once the parasite is present, all the Neons are pretty much done for within 2-3 days. There is no cure. This parasite doesn't affect many types of fish - mostly Tetras. And even closely related Tetras, like Cardinals, can be immune to it. If all of the fish species in your tank died you likely didn't have Neon Tetra disease, as it's unlikely that they were all types of species that could even be affected by Neon Tetra disease.

Feed them just antibiotic food for a week or two, tetra probably still makes it

maybe some bloodworms every few days, but mostly the medicated food

Return it and buy another. If you just got the fish, it came from the store sick.