Won't turn on after reset

I bought a new iPhone and wanted to turn my old one in for a credit. I did the reset on the old phone that sets it back to factory settings and wipes all your date. Then I let it sit around for several weeks before I found time to actually ship it back. I tried to turn it on to just make sure that everything was ready to go and it won’t turn on at all. I figured the battery had run out so I tried charging it. Nothing is coming on the screen at all, it’s totally black. When I plug it into a charger nothing happens. No battery light, nothing. I thought maybe just the screen was fried and it was really on but I couldn’t tell because of the screen. So I tried to get itunes to see it while plugged into my laptop. No joy. I’ve tried multiple cables in multiple computers and charging blocks. All of which work for my new phone but not this one. Any other tricks to try or am I just SOL?