Galaxy s3 wont turn on
My galaxy s3 decided not to work today. It was working this morning. It didnt have a full charge when I woke and idk if it died in my pocket or what. I was using an app earlier in the day that may have used a lot of data/energy at once. At one point I pulled my phone out of my pocket and it was dead. I just assumed it died. But when i got back to my charger, it wouldn't charge. In messing with it, sometimes it would start to turn on or charge but then immediately shut off. I tried changing the battery to no avail. I took it to the at&t store, they thought it might be the battery, bestbuy said they thought it might be something internal, radioshack said battery too.
-when i take the battery out then put it back in, it vibrates and starts to start up then stops.
-when i take the battery out then put it back in with a charger in the phone, it vibrates, goes to the charging screen then stops.
-when i take the battery out then put it back in without my microSD card in, it vibrates and starts to start up and gets a little further then stops.
-when i put a charger in it with out the battery, the red led light flashes then goes out.
-when i flick the side of the phone where the power button is while the battery is in, it'll vibrate and start to start up then stops. (I read something somewhere about a stuck internal power button)
Basically i cant get it past the first few seconds of starting up before it turns itself off.
If any one could give me some insight on to what to do, i would be eternally grateful!