2005 dead battery dangers?

I've spent an hour searching related posts and can't find answers to my questions. Hopefully someone will read this and can help. I apologize for the length of the post; I didn't want to leave out any important details.

I went out to start my 2005 Prius which was working 100% fine when I drove it yesterday. At first, nothing at all happened, on the second try, all the dash icons (including the red SRS) lit up, but the car DID start. I put it in reverse and backed it up and turned it off. When I got out, it beeped as it does if I walk away with the key when it's running, except it wasn't running. I got in and tried to start it, only this time all the icons lit up again, but the car wouldn't start. I tried again, and nothing happened. Absolutely nothing. No lights, no sounds, nothing. I read several posts here and decided to try charging the battery. (My battery charger is a working 15-yr-old 2/10/60 battery charger/engine starter/battery tester.) When I hooked up the contacts and turned on the charger to the 10A setting, the needle popped into the red (test) area and stayed there for about one minute, then flipped into the yellow (charging) area and the car made a very brief "engine sound." After 15-20 seconds, the needle jumped back into the red (weak test) area. The charger has been hooked up now for about 30 minutes, and the leads feel VERY warm. At the beginning of the charge, the dash icons lit up for a fraction of a second and the door warning sounded when I opened the door, but now there is nothing. I don't want to damage anything by trying to start the car using the ENGINE START setting on the battery charger, but I live way out in the country and don't want to pay hundreds of dollars for a tow, either. My two main questions are:

1. Should I try to start the car using the ENGINE START setting on the battery charger?

2. Am I likely to damage the battery if I continue to charge it on the 10A setting for a few hours?

Thanks for any help and information anyone can share.

 

Thanks for the information. I changed to the 2V setting on the charger, but after over an hour, the needle has gone more into the red, if anything. There are no lights or sounds at all when I open the door and try to start the car. I'm assuming that something would've happened by now, if the battery weren't completely "gone." I didn't ask before, but can the car be jumped if the battery is completely dead?

Thanks again.

 

I definitely intend to replace the 12V battery if it proves to be bad. What I'd like to avoid is having to crawl into the back of the car to unhook the hatch, especially since the 20# jugs and cat litter and 50# bags of dog food are still in there from my shopping trip yesterday. I was hoping someone would tell me it'd be safe to jump the car and have it run long enough to open the hatch, but I guess that's not an option?

Thanks again.