It looks sunburned to me. :-/ They need to introduced to the outdoors gradually. I don't know if it is savable. You may want to take it out of the pot and see if it still has roots.

Cactus and succulents really shouldn't be watered on a schedule. They need to dry out in between. It takes some time to learn what each one needs. Many of us judge by the weight of the pot.

It's hard to help with with the care of your others, without knowing what they are. If you know the names, you can google for information, or post pictures here for help.

I know how it is when first acquiring experience in a new hobby. It's a learning process.
I believe if the center cluster is still good, then there's a good chance it will recover after a bit. Agree with jojosplants, check to see if it has viable roots. If so, it's just a matter of time before it recovers. What I would do is repot into a fast draining mix, keep in partial shade 'til it starts new growth, then gradually move into more light.