Roomba Discovery Model 4210 powers on green, but stops after 1 second with power light flashing red. I have tried resetting the battery. The only BIT test that seems to fail is BIT 4b (wall sensor). However I can get it to pass if I hold a mirror against the sensor. And using a digital camera I can see the LED is emitting. BIT 6 (battery sensors), 7 (left wheel), 8 (right wheel), 9 (wheel encoder) seem to be OK. So why does the Roomba stop after 1 second of power on? Is a faulty Wall Sensor and IR Sensor the cause of this problem?
The battery is about 3 years old. However it measures 14.34 V. The Roomba’s runtime dropped suddenly rather than a gradual decline. However it has been a couple months since I last ran it. I use a Roomba Rapid Charger to charge the battery because a few years ago the robot’s onboard charging stopped working. Is it possible that even with a nominally good voltage reading the battery does not have enough energy to power the robot or even run the built-in test?
Separate question: is there a way to repair the onboard charging problem?
Usually when the power light flashes red, this means that the battery is not charged enough for the robot to clean. You may therefore have a hard time doing the built-in tests with a dead battery.
How long have you had your robots battery for? Roomba batteries usually last 1.5 to 2 years with proper care. Did you see the run-time for the battery go down all of a sudden or gradually?
If this issue happened one day to another, there could be an issue with your robots charging system, charger or home base.
If it was gradual, we suggest replacing your battery.
Typically, defective batteries do measure more than 14V without load. Then once it is connected to the Roomba, it will not keep it’s charge and go down very quickly. Especially if you have not used the battery for a few months. In this case, it does appear like you will need a new battery for your Roomba.
Yes, you can repair the onboard charging problem by replacing the robots motherboard. We unfortunately no longer carry the Roomba Discovery motherboards since they have been discontinued for several years now. But, you may be able to find a replacement motherboard or robot sold for parts online.