Hi there,
Thanks for reaching out. I know you state you have tried everything you have found online-- did you see this guide yet? This is the best place to start for “Page Not Found” issues.
If you are still seeing issues after following the troubleshooting steps in there, please check out this Support Guide as well. It outlines all of our build and deploy resources and will get you on the right track 
If none of the above resources help, please write back and let us know. We will need to see your repo in addition to your site link.