Still stops at 15%. I have also tried running fastboot. I get about halfway, but when it comes to the part to reconnect to the phone, it just hangs.
I have tried a few more solutions to no success. Luckily, my phone was still under warranty with T-Mobile for about 2 weeks, so sent it in since it wouldn't turn on (unless you did S/W upgrade mode). Hopefully, they wont notice why. Thank you for your suggestions Bajo.