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Check the oil, it might be low.

Check for turbulence inside the inverter coolant reservoir when the car is on. If no fluid movement, then the inverter coolant pump has failed.

It's always good to know that the 12V battery is good, which in a used car is doubtful. It is always recommended to check that. I like to use a DVM on the terminals, and turn on the headlights to see how much the voltage drops.

It's also good to get a Prius code reader and report the codes for best help. The "mini VCI" is what most here use.

 

You should get the codes read so you'll know what's wrong. I am assuming you replaced the oil during your service, if that's the case, I would suspect the oil is overfilled. If you didn't have the oil changed, then the problem most likely lies at the coils and thermostat. Something wasn't done right.

Also at 145k miles, I would 100% have the codes read by a friend or have the dealer check it. It'll cost you $100 at the dealer but if it's a hv battery issue, it'll save you $3500.

 

Note that the Maint req'd light comes on every 5000 miles to remind you of oil change time. One of things that happens to many a Prius is that owners don't check the oil level, and oil consumption at high mileage is a concern. When the oil is low, going around a tight corner or coming to a stop will cause the oil suction pipe in the sump to go dry for a moment, and the oil pressure goes low. The word "Problem" appears on the display.