Help needed for Dendrobium Burana - continued rot

Hi there!

I recently have expanded my orchid collection and picked up a dendrobium burana (in young bloom form) from a seller. In summary, we had some ups and down - at first I thought it needed more humidity and a plate with water under it seemed to keep things going but then I realized I may have watered it too much because while there was some new growth, the leaves all fell off (due to what I assume was rot). The stalks of this plant seem to be ok (firm, green, one is shriveled) and the spike is still there.

I shared a picture with the seller and they sent a new one - this time bigger - and out of hesitation I didn’t water it. All seemed well until the yellowing leaves started up again. I took a chance and watered it and left it in the bathroom - it’s the warmest place in the house and gets decent humidity. A third leaf looks like it’s on the way out and I’m hoping someone can give me some insight into what to do to help the plant thrive.

For additional context, I used fungicide on the first plant and whether because it was too late or delayed, it didn’t impact the leaves. I also have a den seedling that went through a similar experience but now in the bathroom seems to show new growth. I’m in NJ near the water.

Any insight?