Since it's less than a year since it was purchased, it's under full warranty.
So let GE get it fixed for you!
It has a 1-year parts & labor, plus a 5-year magnetron warranty.
In case you don't still have yours, your owner's manual is online here
It has GE's contact information and the warranty info.
If you don't still have your receipt (tsk! tsk!) GE usually goes by the manufacturer date code on the model number label.