VSC ABS BRAKE LIGHT ON

Without the mini VCI to do this sort of thing, you need to clear the DTC's with another chicken dance:

1. Short pins 4 and 13 of the OBDII port and then make car Ready.
2. Press the brake pedal 8 times within 5 seconds.
3. lights should go off if no problems remain.

These brake codes are stored in nonvolatile memory and can't be cleared by removing the 12V.

 

I would try the procedure in my post before doing anything else. The Prius requires a device that works with those lines (Pin 4 and 13 on the connector) to clear the codes. If the generic device that your mechanic used does not know how to do that, it won't clear those brake codes. A very common situation that people report here is trying to use generic OBDII readers on the Prius. It is really hit or miss to use such, and you never know for sure what is happening, as they can report false readings. Techstream is the only way to go in order to be sure.

It may be that the codes are getting cleared but come back because there is still a problem. Even if the brakes work, there can still be a malfunction.

Otherwise, the 12V battery is suspect, as it can cause brake related glitches at start up if the voltage dips too low. This is especially true after the car has been worked on and has had the doors left open, lights on, etc. Make sure the battery is fully charged.