Bevel modifier not doing anything

Hi Giovanni ggiov ,

Most likely, that is because of Clamp Overlap:

Try disabling that...

Do you have Edge Bevel Weight at the right places?

Maybe post a link to your .blend (via Googledrive, Dropbox or so) here if you want us to take a look at it...

Oh dear,

where to start...

You have not connected the geometry correctly and created overlapping Faces (this is only one Face!):

Also, your Face Normals are inconsistent:

(SHIFT+N will fix the Normals, but first you need to correct the overlapping Faces).

After that, you can assign Edge Bevel Weight where you want it.

Okay ggiov ,

If you Delete that first obnoxious Face I showed, and Reconnect like this, maybe:

So, 'avoiding the buttons', and Fill that area with F, you should have a better starting point (then Select all with A and Shift +N).

Result after that should be something like this:

Even though Press Start is kind of for beginners, in that it is a fun and simple model, it has some hard to grasp concepts when you're just starting. So you can consider starting with the fundamentals and then come back to Press Start. Here's some links:

https://cgcookie.com/courses/blender-3-basics-intro-to-blender

https://cgcookie.com/courses/fundamentals-of-3d-mesh-modeling-in-blender

https://cgcookie.com/courses/blender-mesh-modeling-bootcamp