Carefully lift up the front left and right corners,

then you will need to use a small plastic opening tool to lift 2 clips on the front. The palmrest should flip open and rest over the keyboard.

If you have a N410c, skip this point and go on to the next one. If you have a N400c, disconnect the ribbon cable that connects the trackpoint to its buttons on the palmrest,

Lift the palmrest and then you can flip the keyboard over onto the screen, then you can see and disconnect the backup battery.