Prius won't start...unsure of next steps

I've spent some time looking on here for information but am still not sure what is going on with my car and how to fix it.

I have a 2004 with about 195k miles. I bought it used in 2006 with 17k miles on it. I've never had to replace the batteries or had any major repairs.

Over the last few weeks, it's been very cold where I live. I noticed in the mornings when I would drive that sometimes the interior light and door open light/buzzer would briefly come on. It would stop once it got warm. This same thing would happen if the passenger door was leaned on. Yesterday it started happening all the time, with me having to shut the door three or four times to get the light off. Then, as I drove home last night no amount of door closing or fiddling with the door switch would help. I eventually turned the dome light off. I got home and eventually got the door open light off before heading inside.

This morning, my car won't start. I first tried to start it like normal but just the check engine light came on. I turned the car off, put the fob in the dash and this time the check engine light, ABS light and airbag light came on along with the fuel indicator and the p/r/n/b/d lights all flashing.

I've seen here that it's might be the 12v gone dead/bad? Is that the best option or could it be something else? I've also seen that recharging the battery can be dangerous for the car. Is there a good tutorial or video I should follow? If jump starting the battery works, will that be enough or will this happen again next time I try to start my car?

Any advise or insight would be greatly appreciated...thanks!