This is covered in the text by Paul Smith. Pay attention to the "plus" battery connector: it has to snap back into its place or you will get a nice shortcut!
Reassembly-
Putting it back together is much easier. You may need to clean
up the remains of the rivet heads so they will easily reinsert
into their holes. Make sure the battery connections align with
their respective holes, and snap the unit together, applying pressure
where the six (or seven, if you left that one near the [.] key
alone) hooks are. 
You will probably want to hold the case together at the top with one or two of the rivets there. If you can find a wood screw with a flat or thin head, you can screw it into the body of the rivet and let the head hold the upper section surface. You may need a small washer for this. A machine screw will probably work as well, but will strip the plastic easier and not hold as well. I have only one screw holding mine together and it works fine.
You will probably need to re-shape your tin overlay, as it probably
took a beating during removal. I removed the sticky tape from
mine, but it's probably better not to (unless it really wont stick
anymore). Put wax paper over the tape and put the overlay face
down on a hard cover book. Grab a hammer with a smooth and somewhat
flat head, and pound away. DONT pound away on the part that surrounds
the screen (beveled part). You can probably use your fingers and
a little massaging to fix that area. With a little care you can
end up with an overlay that looks like new. Press the overlay
in place and hope it sticks. If not, a little rubber cement wouldn't
hurt.
Have fun!
Paul Smith
