https://h30434.www3.hp.com/t5/Notebo...y/td-p/6471127 has some ideas on machines and reboots
HP's advice in your case is
https://store.hp.com/us/en/tech-take...t-wont-turn-on
Firstly - is it charged or charging (i flag this because yesterday my HP did the same - luckily her inside pointed out I hadn't turned it on at the wall plug before using it for several hours...................