I've lost my share of miniature roses ... and then I discovered what I believe to be the answer to the whole thing.
They are not truly indoor plants. The truth is that they want to live outdoors. You can plant them in the ground or, as I do, keep them in pots. I'm certainly not a pro, but this is how I would handle the plant:
Remove all the dead material, and prune the healthy stems back by about 1/3.
What size pot is it in? Does it need a larger one? If so, then repot it, and water it well. Don't water it again until the soil is dry to about 1" deep. (If the pot is quite small, water when it's dry down to about 1/2 inch. My roses are in 10" pots.)
Place it in a shady area outdoors during the day, and for the first week, bring it in during the night. Over the next two or three weeks, you can slowly move it into more sun, until it finally is in full sun all day. You can also leave it out a little longer each day, until finally it's staying outside all the time.
I leave my mini roses outside all winter long, but the weather is pretty mild here, as a rule. I don't know what it's like in your area. (In the winter, I move the pots up against the foundation on the south side of the house. They get some sun there, but not a lot, because of the deep soffits on my house.)
I wouldn't advise fertilizing your rose just yet. In general, it's better to wait until a plant shows signs of new growth before giving them any fertilizer.
Good luck! I hope you're able to save your little rose!
I killed several miniature roses, too, until I got soooo exasperated with one that I told it, "Fine. Outside."
