After a time my iRobot Braava m6 mop just stopped working all together.. I did the usual troubleshooting steps, namely: 1. Made sure everything was ready to go, clean and orderly 2. Removed the app (or widget) from phone then reloaded it. 3. Removed the battery waited 5 minutes and then reinstalled the battery. 4. Disconnected and reconnected to Wi-Fi. 5. I should mention that I didn't have any error messages. I called iRobot and they thought it was a dead battery so I bought a new battery ($90). Still no function. I ended up purchasing a new Braava m6.
Just a note: My m6 was probably 5 years old.