So, I did some searching and found a replacement battery online. It cost around $30 for an aftermarket version (find it here
Total time to replace the battery was about 5 minutes - here are the steps.
1) Flip it over -
2) Then you remove the spinning brush (yellow).
3) Unscrew the four screws on the bottom. They do not come all the way out so you don't have to worry about losing them.
4) Lift off the top and check out the dust inside your Roomba. Yuck!
5) Lift out the old battery and replace it with the new one.
6) Drop it back in the charger for a couple of hours so it recharges.
Back in business!
In case you are wondering, the picture above is the small area between our kitchen and dining room. It was originally intended to be a butler's pantry but we figured for this time in our life we could use an extra junk drop area more than a butler's pantry. But a butler's pantry would be nice too! Some day.