if i get 2 motherboards boot them up i can plug in the backlight to 1 psp and the data 1
Yeah You can.
blown fuse.
to correctly check it ~
Plug your black probe in the com input and plug the red probe in the hole with the horse shoe thing(ohm symbol). Then select the Ohm setting on the meter. If you touch your probes together you will read close to 0 Ohms or a connected wire. If your fuse is blown then the piece of wire is broken by the electricity.
Now measure across your fuse to check continuity. If your meter Reads close to zero Ohms the fuse is Good. But if your meter does not seem to measure anything then your fuse is bad.
Make sure your fingers don't touch your probes because that will give you an inaccurate reading (because fingers conduct electricity!).
When your done measure the resistance of your body!