I know this is an older post, but I ran across this when I was trying to figure out why my Deebot M80 Pro was doing the same thing you described here. Also, I was unable to find many answers online. So I started taking my robot apart. I removed the 6 or so screws on the bottom of the front bumper which allowed me to pull the bumper off, which is where i could see that two tabs were broken off. These missing tabs would be the ones to hit the front bump switches when the robot bumps into an obstacle.
I will try to attach a picture. Mine was still under the 1 year manufacturers warranty, as yours could possibly be. I emailed the ecovacs customer support contact I found on their webpage, and they responded within 10 minutes, offering to ship me a new unit. So you may have an option there. Hoping this will help you or anyone else who may run across the same issue.
