stuck at logoscreen

Hi techs, I am wondering if anybody can help me with this laptop. Laptop model: Lenovo ThinkPad P50s 20FL User was writing a document and then left to do something else. Later he came back and seemed like the laptop has gone to sleep, but when pressing the start button, it got to the Lenonvo...

I didn't do any kind of update, it happened overnight. It's not going past the Toshiba logo. Tried with different RAM's, another SSD and without the battery, no results. The only time that did anything different, was when i connected an external SSD with a BOOT partition on it. Any guess what i...