Unhappy HELP! Phone wont turn on!

When i plug my charger in with no battery, The led turns red for about 15 seconds then turns off when the phone vibrates
when i plug my charger in with the battery, I get a flash screen showing a battery with a "refreshing" circle in it, The phone then starts to boot, Gets to the Samsung galaxy s3 screen and then dies.
When i go to download mode, It runs for a few seconds then dies
when i go to recovery mode, It runs for a few seconds and then dies.

I have no idea what to do, I do not have a warrenty.
If anyone knows of any fix to this please let me know.
Im completely comfortable with taking phones apart and im not scared to solder.

Please help. Im lost.