Roomba: the amber (yellow) light is flashing fast all the time.
If Roomba senses that its battery has been significantly discharged, Roomba will enter a special 16-hour refresh charge cycle. When the 16-hour refresh charge is initiated, the CLEAN light will quickly pulse red/amber. Do not interrupt the cycle once it has begun. The 16-hour refresh charge cycle is initiated by the robot and cannot be started manually.
For long-term storage, always remove the battery from Roomba and store in a cool, dry place. Blue or black batteries should be stored after Roomba has been used. Yellow batteries should be stored after being fully charged.
Battery capacity reduces overtime and usually the battery will need to be replaced each year.