Hi,
You IR sensor might be broken and needs to be replaced.
Did you buy the robot with RobotShop?
I have a Roomba 550 that needed a new battery. I’ve installed the new battery and I can hear some faint “white noise” coming from the Roomba, but other than that it appears to be dead. Any suggestions would be great. 
Hi Susan,
It may probably due to a defective motherboard.
Did you buy the Roomba with us?
Hello, I have a Roomba 500. It started to go in circles (clockwise - to the right), but it keeps doing that without giving any error message. I checked the right wheel because it seemed not to be turning, but there was no hair or anything bad on it. I opted to buy a new right wheel, but after installing it, the Roomba keeps going in circles. I cleaned the connectors with electronic cleaner, but nothing.
@Marcelo if you have replaced the right wheel and it is still doing the behavior, it’s possible the problem is due to the motherboard.
@Mathieu, thanks for answering. How can i get that fixed? Is that spare part available? Can I change the motherboard myself?
@Marcelo Unfortunately, it is not available in our store, we suggest you third party websites, such as eBay.