I am a blender user and I find it more suitable for personal artwork projects due to its flexibility and being an all in one solution. But recently I decided to make some money on modelling and since lots of studios use maya(I think simply because they prefer stability over flexibility. And maya has more professional plugins) I am trying to learn maya.

I am trying to model a electric guitar on maya, since I think it is a good shape to model to understand most of tools, and I was doing things as I would do on blender. But it seems there are some holes maya cant fill. Regardless of what I tried maya resisted to make a box out of 3 walls connected by 2 edges. Here is screenshot. Please help me.