MM ------ as this thread has the title of 'cattleya rot' ----- I will mention some nice things that give all orchid growers confidence/hope in orchid growing. I haven't had a catt rot or even die in over a few decades of catt growing. I have lost a total of 4 catts though ----- but this was back when I first started orchid growing. That was when I was a newbie. But learned some important things from that - which amount to just a short list of tips ----- quite short. And sticking permanently to the basic tips definitely helped me have no issues - zero issues.
Although ----- I did inadvertently scorch a few catt leaves during peak sun scorching conditions - for some of my sun-hardened catts, but was not life threatening. All under control.
One main thing I stick by is to try make conditions tough for whatever unwanted organisms might/could grow inside the pot and/or in/on the roots ..... and also on the leaves and stems.
The way I water - is by sending most of the water into the media toward the outskirts of the pot ----- have the water flow into the media toward the sides of the pot. Pretty much like a waterfall cascade down into the media - the region along the walls of the pot. The media there gets very wet, but a dry gradient toward the centre helps with water movement and evaporation and humidity within the pot (or that's what I reckon anyway). My pot is wide enough so that the media in the whole pot doesn't get water-logged/saturated when I do the watering. The roots of my catts are generally regular ones ----- the ones that are not adapted to watery growing conditions.
I put much less water toward the centre of the pot ----- and sometimes none. The roots sometimes need to get their nutrients, so I figure that they at least sometimes need to get slightly wet in order to pick up whatever is still hanging in the media (like fertiliser, mag-cal etc). I apply 'weak' fertiliser and mag-cal ---- just once a month.
I do watering generally each morning. But watering every morning is not actually necessary. Even in very dry conditions, I've had somebody help me with manual watering (spray wand) with 2 days of no water. I just like to get in there to do the watering each morning - which allows me to keep an eye on all my plants ------ just to make sure they're all fine.
Sometimes - I allow the media to just dry out - including the roots, which probably does make things tough for certain unwanted organisms that might want to do their stuff inside the pot and in/on the roots. I just so happen to grow all my catts in scoria. I'm sure that I could grow bark or bark/perlite mix too. But I just use inorganic media in my tropical conditions.
Natural and gentle air-movement is good in the growing area. The air moves around the leaves and stems and all, and down through the media in the pot. My pots are all good drainage ones - sitting on drainage grates, that prevents the pot bases from sitting in any drained water. The drainage grates also allows all holes to get air into (and out of) them.
The temperature is generally quite nice for the orchids, and the roots are never watery and cold for any lengthy period of time.
So after a few decades plus ------ zero issues -- no losses of any catt, and no rot. But I did have a dendrobium beetle chomp a flower spike in half and even take out a catt leaf this season ------ but dealt with nicely by using carbaryl.
So for orchid growers out there ------ when the growing conditions are continually kept satisfactory ----- continually ----- the orchids can really do what they're supposed to do - grow nicely and healthily indefinitely. If the nursery growers at orchid nurseries can grow their plants really well, then so can us home grower orchid fans.
Although - I do have the benefit of tropical conditions here, which cuts down on a lot of effort, as compared with snow country conditions etc. But the same thing applies ------ aiming for continued satisfactory conditions for the orchids to grow.
I'm also posting this because your orchid didn't make it due to rot. So just mentioning a little about what I do for my orchids at home ----- so could possibly become useful to somebody else too. Each grower has their own ways of doing things. We just pick and filter and eventually all come up with a system that works well for very long times.