6. Insert the battery making sure, again, you align the correct polarity.

7. Once you've inserted the battery, you can breathe a sigh of relief. I'd recommend you double-check the quality of your soldering work by using a digital multimeter to check and ensure the board is getting power from the battery. Just touch the tips of the multimeter terminals to the appropriate spots on the board as shown in the picture:

 

 

 

 

 

If everything was done correctly, the multimeter should read somewhere around DC 3.68 volts.

8. You will need to shave off a small bit of plastic to make the battery retainer cover align correctly. There is a small SMD device (D5) just in front of the positive (+) terminal which will block the side of the lid. I use the Dremel with the sanding disc to shave of a little corner.

9. Mount the retainer on top of the battery holder.