rick reynolds, #363.xxxxxxxx indicates that this microwave is build by either GE or LG. The F3 error code is an indication of a stuck key panel. Unless you are used to working with microwaves, I do not recommend to work on it. Even when unplugged, there are some components that hold a charge of +25.000 volts. So unless you know what you are doing, I recommend getting it properly service or replace it with a new one. Hope this helps, good luck.