Does it need to be cleaned?
The cleaning light indicator light signals that the unit needs to be cleaned. The cleaning light will continue to blink for quite some time - the equivalent of three brew cycles.
Was the cleaning cycle interrupted?
Do not unplug the coffee maker during or immediately after the cleaning cycle. Unplugging will interrupt the cleaning cycle, and you will have to start the cleaning cycle again.
If you don't wait for the entire cycle to complete, and unplug the coffee maker immediately after cleaning, it will continue to blink. It can take a while - up to the equivalent of three brew cycles.