Phone is dead but thought I'd share my troubles on xfstk's side in case someone else faces the same problem as I did.
1. Started and did everything on the original post, encountered Windriver Error: 0x20000015. I tried both method but it didn't work, to the point that I build xfstk in linux only to find it still throws errors.
What fixed it for me was to hold down the volume down button before I connect the cable to my laptop for whatever reason but it worked.
2. It then still gave me an error but I forgot what it was, I didn't save the logs until much later. Scouring the thread someone suggests providing a soft fuse file. Okay. I downloaded the file from him BUT xfstk gives me error code 45 softfuses signature error. I had to download the raw firmware from
here to get the soft fuse file to get it to work.
So there it is. In the last "successful" attempt xfstk gives me "Success: Download of FW and OS Completed." but of course the phone didn't cooperate. I think you should add those to your original post, especially the first one since it helped a lot of people.