When I first got my
When I first got my microwave kiln at home I wanted to add some decals to some cabs I had fired in my kiln, they all went ka-boom. After I stopped being mad I looked back at what went wrong and I agree with Piranga, I heated the glass to fast, so I went back and tried a couple of things, I put the piece of glass in the microwave ( no kiln) for 30 seconds on high and then when it was warm to the touch I put it in the kiln and used the defrost setting for 30 seconds and then the full power, no exposions. I also heated the piece with my heat tool until it was very warm and then put it in the kiln, again no explosions.
Try experimenting with the pieces that broke if you still have them.
One of my student has gotten really good at doing textured pieces in the microwwave, so anything can be done, it just take time and experimentation.