Samsung Galaxy S3 — Yellow warning light

i have had my galaxy s3 for about 2 yrs and recently the phone has not been charging, i assumed it was just my charger, but i bought another on, this one worked but the wire had to be placed in a certain way for it to work, so i tried another one, same problem. but it was still charging, but today my phone showed a yellow triangle with an image of a battery and a little symbol inside the triangle (not a thermometer i dont think) and now the phone is completely dead and not charging, i have taking battery out and tried a new one but its completely died, pls help!?