Why won't my Galaxy S3 boot for more than a few seconds?

[AC Question]

Galaxy S3 won't boot for more than a few seconds

So starting yesterday, my wife's GS3 will only boot (vibrate and go to Samsung and SOMETIMES GS3 screen) then turns off. I've tried the recovery mode, etc modes... and it will start booting, but turn off fairly quickly.
This phone is almost 3 years old so i'm ok with it being time for her to get a new one, but I'd like to at least recover some data from it. Any suggestions? I've tried different batteries, chargers....

Thanks!

 

[B. Diddy]

Re: Galaxy S3 won't boot for more than a few seconds

Welcome to Android Central! When you tried a different battery, was it fully charged before trying to turn the phone on?

If you can't even boot into Recovery Mode, it might be very difficult to get any data off the phone, since it won't stay powered on long enough for anything to access it. How much of the data has been backed up or synced? Are we talking mostly about photos?