Bought a used Prius during Superbowl week.

Not that I know. I had no problem logging in to the Toyota site a few weeks ago.

 

Have you checked your spam/junk folder? Check also on your email provider's server, as they also could be spam filtering.

 

You're only getting 250 miles out of a full tank? Should be getting 350 miles at a minimum more like 350-400 miles a tank.

 

The Prius should get better mpg in the city than highway. My mpg goes down slightly when I do lots of highway driving, goes back up with city driving.

 

My youngest Gen 1 Prius has 140k miles... the oldest, about twice that. I do most of my own work on the vehicles.
Yes, Prius city MPG is somewhat better than highway 'because the battery does more of the work at low/no speed .
Yes, your miles per tank will improve once the battery problem is fixed, because right now the gas engine is doing more work than necessary to manage charging the battery over the fault that it sees.

To your problem: Since you describe yourself as mechanically "timid", you either commit yourself to find someone you trust to work with you to maintain the car, and be prepared to spend some amount of $ on it, or bite the bullet and part with it.
Alternative #3 is to acquire tools and earn to work on your own vehicle; but that option depends on your circumstance.

All cars require maintenance.
Longer term, it's always cheaper to repair than replace, but there are occasionally big bumps in the repair road.

There's some math to be done. At $2.50 per gallon, a Prius at 35MPG costs $0.072 per mile to drive. A replacement vehicle at 25MPG costs $0.10 per mile (both models ignore oil, tires, etc). Prius economics improve at higher gas prices. So today, a $100 repair to a Prius is recovered in (100/(.10-.072))=3570 miles, ignoring any "loss" from a trade-in, and assuming the replacement vehicle has no needed repairs, either. So that's a consideration in the repair vs trade economic decision.

Good luck with your choice.