How to recover from a broken plugin
Installed a plugin and it broke my system. Nginx came back with "Broken Gateway" I knew that the problem was that plugin since it was the last thing I did.
./nodebb reset -p plugin-name
Plugin gets removed and the forum is rebuilt and everything should work again.
This was my fault, I installed the youtube plugin without reading the notes that said to use the later version . Moral of the story, read the docs before rushing in