In a previous post I recounted how a brake issue was perturbing the hybrid battery. After having the brake job done, a few weeks later (but not much driving in terms of miles), the (red) brake light and the (yellow) ABS light with the circled exclamation mark appeared on the dashboard. They would appear upon starting the car, remain for a while, disappear, reappear, while driving. Also, I noticed that the car was braking in a very weird (and non-reassuring) way, as if I had to apply more force to the pedal. Also, upon starting the car, the car would start moving on its own a little bit (again, not reassuring) and, upon turning the car off, the brake pedal would move by itself.
I called the same shop and they said they would have to run an ABS test ($100+ dollars) and take it from there.
I looked online, thought for a while that it was the inverter coolant pump. I checked as shown here and there were some bubbles.
Any hints as to what is going on?