Electric Pressure Cooker

Howdee, I need help. I just purchase a brand new Electric Pressure Cooker and have an awesome recipe for baked apples. I prepared the apples, cored, filled with brn sugar, walnuts and raisins and put in the pressure cooker and FROZE. I took them out and put them in the microwave. When I was a young gal my mother loved her pressure cooker and one day made a soup with tiny pastina. Well she put the whatchamacalic on top and when it finished dancing, the pressure cooker exploded and seeing as we were not wealthy enough to have a maid, I became the maid and it took me weeks to capture all the pastina. So you can see my reluctance in using this fine piece of equipment. So if anyone can offer any help, it would be greatly accepted and appreciated.