Use the flat end of the spudger to push the battery tray out and away from the keyboard.

The tray is held in by small "ears" and may take a significant amount of force to dislodge.

If you're having trouble, use the end of a spudger or a flat blade screwdriver to "walk" the tray out, pushing on alternating sides instead of directly in the middle.

Remove the battery tray.

During reassembly, firmly push the battery tray into its slot until it clicks into place.