I had the same clean brushes error. Disassembled the unit completely and cleaned every rotating part. After reassembly, I got the same error message, however, I noticed the brushes weren’t turning at all. It didn’t make that same grinding sort of noise. Ran really quiet till it shut down. Dissembled the unit again and removed the roller brush module. Removed the motor and jumped it using the recharging base. The motor ran. Reassembled and ran the unit. No error message. So far, so good.