Mini phalaenopsis with wrinkled leaves, shrivelled roots

[Vivy]

Hi people!
So I'm basically a beginner at orchid planting and even gardening in general. I'm learning new things everyday and being able to see your plants thrive is such a rewarding sight! So around last December, I picked up 2 very pretty mini phals. One of my phals is doing very well. I can see new root growth as well as leaf growth as well. My second phal however, isn't doing so well.

Keep in mind that when I bought these from the store, I didn't look at the condition of its roots at all (I didn't know any better), but it appears as if I had bought a phal with roots that you wouldn't consider optimal. I didn't think that it would pose a large problem because the roots and leaves were fairly green. However, the leaves of my second phal are beginning to yellow and wrinkle and the roots themselves aren't plump like my other healthy phal - they're shrivelling. What should I do?!

I water my phals when the roots appear silvery white and the media feels dry. They are potted in plastic pots with a drainage hole on the bottom. I have also created additional holes on the sides for additional drainage. In addition, I have also cut away the rotten, dead or black roots.

I have no idea what is happening to this specific phal, so as an orchid noob, can anyone help me out?

Oh, and also, there is no new leaf growth or root growth on this problematic phal, unlike my other one.

[Vivy]

Pictures!

[reliablefool]

The leaves and roots look fine to me. The yellowing looks like too much sun or a touch of sunburn. I could be way off-base, but that's what it looks like to me.