Need help with monitor not turning on.

Hi, I recently got a used LG OLED Ultragear 39GS95QE-B.AUS. But when I plug it in with the pc off, all I see is "no signal".

But when I turn on my pc with my original two monitors and move the Display Port from one of the monitors to the LG one, it works just fine.

I have tried updating my drivers, and even tried to update my bios (which there was no update option available). I have even tried to change from a Display port cable to a HDMI cable (with me also changing the input on the monitor itself). But the LG monitor only shows no signal.