"Pokemon Go to the polls" was just a silly meme. I think voters wanted somebody to the left of Obama, and Hillary felt like a big step back to the '90s.
Dissing Bernie's platform didn't help. One key moment I remember was her saying that Medicare For All was something that would "never, ever happen". Instead of adapting her platform to win over Bernie's voters, she just dismissed it completely as foolish pipe dreams. Just really tone deaf and smug about it.