I'm on a friend's laptop and am not used to the keyboard of it, so if I make spelling errors, bare with me.
I'm sorry your snake died. I don't know what I would do if my burm died. I am so terribly attached to her. I'm going to give you some advice on husbandry so maybe you can revamp the living conditions of your other snake so you don't have to go through this again.
First and foremost, throw away the hotrock. They are notorious for causing burns on reptiles. They get too hot in some places and not hot enough in other places. Replace the hotrock with an under-tank heater of the appropriate size. You'll want to put it on the same side as the lamp so that your snake can regulate its temperature by going from the hot side of the cage to the cooler side of the cage until it gets its internal temperature where it wants it.
Next, go to the petstore and get 2 digital thermometers (a cheap one is the Zoo Med Digital Thermometer with probe) and a digital humidity meter (a cheap one that is combined with a thermometer is the Zilla Digital Thermometer / Hygrometer with probe). Don't get dials or stick-ons. They rarely work correctly.
Put one digital thermometer on one side of the cage (the hot side) and one digital thermometer on the other side (the cooler side). Make sure the probes from these thermometers are at the level of your snake, not up by the heat bulb. You can also get a temp-gun, which will let you get the temperature of anything instantly just by pointing the gun at it.
A temp gun is only as good as how often you use it, and a thermometer is only as good as how often you look at the readings it is taking. Proper husbandry takes time and effort.
Your hot side should be about 90 and your cool side should be about 78. It can drop to 75 at night, but no lower. The warm side can drop to 80 at night.
To keep the temperatures where you want them, you need appropriate-wattage bulbs and an under-tank heater of the appropriate size, and plug them into a thermostat. A cheap thermostat is the Zoo Med 500R thermostat with probe. Google it to find a place that sells it. I'd give you a link, but I don't want to risk my post getting pulled.
Humidity is very important. It needs to stay at 50-60%. If you are having difficulty keeping it where it should be, invest in a mister system (a good, cheap one is the Zoo Med Habba Mist Auto Mist System). Of course, you can accomplish what a mister can if you are willing to spray your cage multiple times a day with warm water in a spray bottle. I find the mister to be more convienient.
The overall BEST way to keep humidity where you want it is to have a good cage. Cages with a lot of screen will do nothing to keep humidity in. In fact, if your cage just has a screen top, you should cover most of the top with tin-foil and tape it down to keep the heat and humidity in.
You're going to have to get a new cage if you ever expect to keep your other snake healthy. Square cages don't let you create a temperature gradient. Screen destroys your ability to keep humidity and heat in. This will be your biggest expense, but it is necessary. Choose a large rectangular cage with a front-opening door, solid sides, and preferably a solid top that has ventillation vents and a spot for the lamp. However, like I said, you can cover most of the screen if your cage has a screen top.
You can make your own cage, but because burms grow fast and are STRONG, your cage will need to be large and strong too, which can pose a problem for amature carpenters. Expect to spend an absolute minimum of $250 to get an appropriate cage.
As for bedding, you didn't mention what you were using, but I personally use pillow cases and wash them and change them every time the snake "pees" or poops. This, however, does nothing to keep up humidity. You can use cypress mulch to keep up humidity, or aspen, but DON'T use these beddings: sand, millet, walnut, pine, cedar, or alfalpha (sp?) meal. Make sure you clean out spots that have been soiled as soon as they have been soiled or you run the risk of your snake getting an infection.
Lastly, don't keep your snake with another snake.
Sorry for the wordy reply, but a lot of people were telling you that you were doing things wrong, but not telling you how to do it right. I hope I've helped you, and PLEASE don't let this advice fall on deaf ears.
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~Sara~
"If you look down on me, I am evil, If you look up to me, I am God, if you look straight at me, I Am you"
-Charles Manson