really works.
After struggling with bad accumulator I bought a replacement from Ebay. Cleaner with bad battery worked maximum 10 minutes. New battery was good for a couple of cleaning sessions, but then after a longer idle time I got the error above. It was very unpleasant situation, because just bought a new accumulator and another error came out. Atfer short googling I decided to proceed with solution from Youtube. Disassembled my Roomba, but did not see any corrosion. Just small amount of yellow stains. Almost invisible. Despite of that I decided to clean the area with alcohol. And it helped. Error disappeared. Apparently there are located some sensitive feedback circuit for battery voltage or current detection.
Here you can see some tips on disassembling iRobot Roomba