As Ruslan said, it’s a common problem with the Gen 2 Prius, enough to where Toyota extended the warranty on the part to 10 years from service start. If your combination meter (that’s what it’s called) goes faulty within 10 years of the car first being in service (you can check that date on Toyota tech info site by putting in your VIN), they should replace it for free. If not, I was quoted at two nearby Toyota dealerships, one for ~$550, the other, nearly $900. It also means your car will be in service for around 3-4 days as they have to order the replacement board with your proper mileage, wait for it to arrive from Toyota, and then install it.
You can order a refurbished board online (Google is your friend here) for about $150 if you don’t mind taking the entire dashboard apart. Luckily it’s pretty easy and there are YouTube videos out there showing exactly how it is done. Luckily, you can drive w/o the combo meter without hurting the car at all, you just have to track your fuel usage and mileage for oil changes and the like.