You can now see the circuit board with battery.

There are actually two circuit boards stacked on top of each other. You can leave the hidden circuit board (with the display and controls) in place for this repair.

Remove 6 connectors from the top circuit board. Pull these straight out. there are no locking mechanisms. From left to right they are Red, Black, Yellow, Blue, Blue base and Black base. The colors are nicely marked on the circuit board.

The ribbon cable does not have a connector, so don't remove it, leave it in place.

Push in the plastic tabs holding the top board in place to release it, and fold it out on the ribbon cable to expose the underside of the clock battery.

Don't remove the bottom board! I did this and it was a big pain to get it correctly reseated so that the control buttons worked.