Roomba Madness

My Roomba was no longer holding a charge. So I did what anyone would do. I bought a new battery. I put in the battery, let it charge up. When the power light turned green, I started it up and it did its job.

Back on the charger, the new battery isn't charging. I've now plugged the charger directly into the Roomba (instead of the base) and the power light slowly glows on and off red, never turning green.

I think this is a bad sign. :(