Was that a console battery warning, or ISS? (the message will say something low battery on station 1 if it is the ISS battery)
Check again today, since you posted before midnight. Typically, the low battery warning will clear at midnight if the battery was replaced. I assume that this second battery was installed yesterday? (Sunday)
If you don't already have one, you could get a cheap digital multimeter and measure the battery voltage to confirm whether it is good (>3V).
Greg H.