2010 won't start after vacation, whirring and red power light

Hey, not sure if I messed up my startup or what. I've got a 2010 Prius, no idea of the model. Totally unaware of the workings of cars and have no means to repair anything. Last time this happened in 2017 I had a dead 12V and had to get it replaced, but this time it's behaving differently. Trying to figure out if I can get away with a jump and 20 minute drive around tonight or if I need to take it in tomorrow for more severe repairs.

The car is parked outdoors in Chicago, it's cold. It hasn't been started in 20 days or so.

Tonight the doors unlocked with the fob, but I messed up and hit the power button before hitting the brake.

The check engine light came on briefly, the power light turned green briefly, and the dash said some sort of message which I didn't get a chance to read, because I panicked that I'd forgotten to hit the brake and immediately hit the power button again to turn it off.

I then immediately hit the brake and power button again, but this time the LED on the power button was red and the dash said something about being parked on an uneven surface, which it isn't. I tried to set and unset the parking brake, it still wouldn't come on. The uneven surface message appeared twice.

Now the power locks won't fire, the dome light when turned on is flickery. It's too dark outside to see anything else and I live alone with nobody to help check if anything else is working while I'm in the driver's seat.

When I walked away to my apartment (where I can't see or hear the vehicle) it was whirring like it normally does after I turn it off, but the whirring was slow and quiet and not stopping.

I'll call the shop tomorrow if I don't hear anything, but would appreciate any advice.

EDIT: OK I just got back from fiddling with it downstairs again to confirm if any lights were coming on. The underdoor light comes on but nothing else. No brake lights, no headlights. This time the brake pedal was VERY hard to press down instead of its usual easy weight.

 

Thanks! A neighbor has offered to help me jump start it tomorrow so I can get it half a block down the road to the repair shop. (Would have been today but I've been awake 20 hrs!) I guess it's the 12V again. It was a refurb when I got it so 4 years is not unexpected. After all, my neighbors buried me completely in 8 feet of snow last winter and I couldn't dig myself out for six weeks. My car has it rough.

I don't know what a low amperage charger is and don't know what you mean by "put the on the battery jump spot under the hook in the fuse box". We have circuit breaker boxes in our apartments, mine is about 400 feet from the parking space and several stories up in the air.

I do see that there are solar-powered trickle chargers. Is that something you have heard of, and if so are they useful or pieces of junk? Would they even work for a Prius if set on the dashboard? I can't have anything sticking off outside or it'll walk away. The car parks in an unsecured outdoor lot. Might not work on snowy days which kind of defeats the purpose but I don't know any other way to get a trickle charge on it.

 

Update for those who come later: It was indeed the 12V battery. Neighbor jump started me, I drove it around for an hour, then took it to a shop down the block. They had to jump it again in the parking lot to get it into a bay! New one installed. Thanks for all the help.