iMac screen is blank when I start up

I purchased a new iMac 24-inch 2023 last November (Sonoma 14.4.1). I just started to have this issue about 2 weeks ago, occasionally when I start it up, it makes the sound that it has started up, but the screen is blank and appears to have a very slight light coming through the screen (dark gray not black). I have waited up to 20 minutes and nothing happens, so I have to hold the power button to force it to shut down.