Prius 2000 screen error message...power problem

Lat night, symptoms my Prius 2002 displayed after local deal replaced the 12V battery:

Screen warning popped up with red triangle, saying "PS" then "main" with a battery, plus a "!" through car" icon. Also, power problem, hesitation.

Since I picked up the car, I probably drove a total of ten minutes before this error message came on and I started having problem.

Glenn

(Prius with 2002 with 87,500 miles)