I wish I had good news for you, but I do not.
The hole that you mention is a serious matter. The hole means that your microwave, if it operates, will now emit harmfull magnetic radiation. It is no longer contained within the microwave. It can be harmfull to anyone that is within a couple of feet to it. Its not likely that patching the hole will solve the hole issue. A faulty or overheated magnetron can cause this problem.