1.The OP is enough
![Smile :) :)](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7)
2.The only thing that can bring you to fastboot only mod is when you red "NEVER wipe System or Persist!", you thought but it's here for a reason so it's better to wipe
![Smile :) :)](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7)
Yes for a reason, people wipe it, not knowing what it is and nevermind they told not to
![Smile :) :)](data:image/gif;base64,R0lGODlhAQABAIAAAAAAAP///yH5BAEAAAAALAAAAAABAAEAAAIBRAA7)
3.TWRP you need only to know what the hell is the name of this satanic device you bought as a phone and use latest version. And even if version you have used is no good, read 100500 posts: "Can't boot TWRP when looking north, i have flashed it while looking south!!", there always a good version suggested. And if you haven't wiped system, you can always reflash TWRP and boot into it.
4.It's sometimes take +-5 minutes to boot fresh custom ROM