Help with hacking BB-070 pad

Ok so I happen to have this pad left over so im gonna stick it in my nuby tech SFA stick. The thing is im not really understanding this diagrams. Or maybe I am im not sure.

Is it that left and up share the same ground?
And down and right share the same ground?
same with Y and A?
and X and B?

I see back and guide have there own ground but what about start?

Also how about RB and LB?

anyone who has hacked this pad before im hoping will be able to help me out with this

thanks in advance.