Why won't my mac start up?

When I try to boot up my mac it doesn't turn on at all. It's charged and I've tried different chargers and they all work fine. A similar problem happened in the past where it shut down after the Apple logo appeared when I tried to boot it up, and I solved that by restarting it one of the times I was able to get onto the lock screen. This time around it's not even getting the screen turned on, except one time where I couldn't get to the restart button in time. I've tried giving it time to just sit there, however it seems broken.