ios14 download killed phone

I have an old generation iPhone SE. Last night it was downloading the new iOS. I believe 14.

This morning the phone screen had a dark bluish-black color like it was sort of on, but not. I held the on/off button until it went off. waited a few minutes and started it. The bright white apple screen showed for a second and then it went back to bluish-black screen. What is going on?