The battery is very small, and it must be located on the systemboard/motherboard.
So you do not see anything on the screen at all when turning on the computer?
Have you tried turning on the netbook without the laptop's battery (only with the charger connected)?
When you see nothing on the screen, the CMOS battery is not the issue.
You do not even need the CMOS battery for the computer to work (but CMOS battery would keep the clock running and other settings).
Since you've tested the memory and hard disk, then the issue is the systemboard/motherboard.