Nissan Sentra won’t start

Hello, new to forum. I have 2011 Nissan Sentra 2.0 the other day came home from work and parked my car. 1/2 hr later went back out car won’t start. No dash light or radio. Today I got jumper cables and tried to jump start the battery using my wife Toyota rav 4. After revving periodically for almost a 1/2 hour the radio is working but car still won’t turn over. It has been very cold where I live lately. I have never had any issue with starting the car. Is it likely the battery is just toast and I have to get a new one or could it be something else. I don’t have lots of money so even buying new battery is going to hurt the financials. Just don’t want to buy a battery if it could be something else. When I try to turn car over now rpm looks like it is jumping a little and clicks when I try to start. Any ideas would be helpful as I am not a car guy

Make sure your connections are tight and clean. Take the battery somewhere to have it tested.