Previous Storyline issues

Cannot finish the last storyline “Terror’s Reign” even after killing Diablo twice. Have had a friend help me. When he clicks on door he gets a raid window. All I get is and “E” to enter and it only enters me. I did it once today and diablo appeared with 194million hit points. When doing it with my friend he had like 80 million. We killed him twice and I got no progression with the storyline. I have been at this for hours and am getting so frustrated with this entire process. I cannot move on to the new (March 25) storyline until I finish this. If I can’t finish this then I don’t see any point in continuing on with this game! I am beyond frustrated.

The storyline quest has to be done alone. It’s true that they made it a bit too hard, but it’s 100% doable.

I have tried 4 times and failed. I can’t handle 30 min of continuously spamming my keyboard. Even tried on a lower paragon lvl and it changed nothing.

Difficulty doesn’t matter. I you might have to change your build to be able to defeat him solo.