Samsung Galaxy S3 — Galaxy S3 wont turn on after attempted factory reset

I just got a new S5 and was planning on giving my old (still working) S3 to my dad. I started doing a factory reset to wipe all my data and left the phone on my desk. When I came back to the device a few minutes later I discovered it's completely bricked. Won't turn on/respond at all (I attempted all the hard reset key patterns/power drains I could find online) and the red LED charging light doesn't even turn on when it's plugged in. It only comes on if I plug the phone in without the battery, but the phone still wont turn on. I also have a backup battery so I tried switching it out, but there was no difference.

Is there anything else I can try to salvage this phone? Or is it an expensive paperweight now and my dad is S.O.L.?