What I would be looking for on photos of the leaves is sunburn. You indicated you had it in direct sunlight for some time, and that could cause the blooms to blast. I would also expect to see some large black leathery areas in the leaves if it were sunburned.

the blooms dropping in and of itself is not necessarily a problem...all living things die, orchid blooms included. It is a bit unusual to see the bloom spike turn brown so quickly, so I thought perhaps sunburn.

At any rate, if there is no other apparent problem with the plant, I would simply cut the bloom spike off and continue to grow the plant. Very sharp sterile blade.....cut the stem about an inch or so from where it emerges from the plant. If you have it you might dab a bit of fungicide on the cut...others use Cinnamon...yep, that stuff you use In cooking.....the powdered, of course. I, on the other hand don't use anything on my orchids. See how cut and dried all the rules about orchid culture are.......☺

How you are growing the plant.....This is important, because you really can kill this thing before the owners return if you badly goof with some of these steps.

light.....When the plant is receiving its maximum amount of sunlight, if you hold your hand between the plant and the sun, you should be able to detect a light shadow on the plant. As you have discovered, direct light is a no-no.

Water....critical.....the plant is in a pot with multiple holes in the bottom. These are critical for air circulation and water drainage. It looks like you may have the clear pot in a container of some sort in the last two photos. Growing it in the container may not be the best for the plant, especially if the container has no drainage holes. The container will restrict air flow, and if no drainage may collect water allowing the plants roots to stand in water. Your first photo does show a root that appears to have been sitting in water, and the end is rotted.....there is a new healthy branch that has come off that root, and appears to be growing fine.

When your plant gets almost completely dry.....pot feels warm and light when hefted in your bare hands.....water it. Take it to the sink and just flood the pot with water.....Just give it a good soaking, and then let it sit there in the sink and drain completely before you return it to the growing location. If you are growing it on something that moisture will damage, put the pot in a plate or bowl. Submerging it for 30 minutes is another of those "hard fast rules" that appear from time to time in orchid culture......Wonder what a commercial greenhouse with thousands of plants would do?

Let the pot be until it again gets almost completely dry, then do the watering thingie again. This can occur anywhere from 3 to 7, or more, days, depending on your growing temperature, humidity, and air movement.

If an orchid plant sits in water for just a couple of days, root rot can/will set in and destroy the entire root system under it, and at that point it becomes very questionable whether you can save the plant. Don't let that happen.

Don't know where you are located, but its summer in the Northern half of this big ball we all live on. Unless you live near the very top of that ball, you can grow that plant inside or outside the house. What is comfortable for you is comfortable for a Phalaenopsis. Just do not let night time temps get much below 60 degrees F.

I hope that's enough rambling to ease your concerns, and get you trough your baby sitting period. Just be forewarned, there is a "bug" in every orchid plant, and if you are bitten by this "bug", the resulting disease....Orchiditis....is for most, incurable. You find yourself poking around big box stores and garden centers looking for orchid plants to take home and fret over, and then find yourself on sites like this trying to get answers to all those horrible questions that you don't know the answer to. And should the owners of this plant decide to bring you an orchid to show their appreciation for what you did for them, welllllllll, welcome to the club.

Bill