I think my phone died, I think.(Samsung SGH-T399) Please help if you can. Thanks!

Hello people's! I woke up todayand my alarm went off on my Samsung SGH-T399 phone, It's unlocked and has been working perfect, i've had it for 2.5 years, and I unplug it from the charger, (it's at 100% the battery) and it works great. 2, 3 minutes later it shutted off, and then on about 5 times, untill it no longer will turn on. if you guys have any ideas and can help, it would be great. thanks

have you check the condition of the battery? is it bulking?

nope, but im suspecting that the swm-recovery is broken. I tried flashing it direct with roms on a micro sd and with other roms on odin on windows. but no luck it seems that when I press the wipe data,etc option on the swm-recovey on my phone it crashes and restarts. sooo what I need to find out is how to repair the Recovery menu on my unlocked phone. haha I cant to find any answers on the internet so far for my model. damn samsung ha I guess I should buy only popular models..