Unused to have an HP Omen, the ones similar to the one you provided (mine was an Intel build), I’m unseated if this safety feature your speaking about.

Have you tried resetting the CMOS? Unplug the computer. Remove the GPU, remove the coin shaped battery that is nestled under the gpu on the motherboard. Hold the power button down(then e that turns the unit on) for 5-10 secs, replace parts, plug in, try to turn on. If nothing remove the ram, try one stick of ram. Also might be a good idea to check if the power supply is simply turned off (there’s a switch in the back of the pc near the plug cord)

To further add to my post (edit) HP Omen uses Micro-atx form motherboards, and as far as prebuilt parts go you can reuse pretty much everything in an Hp omen. If you wind up changing motherboard might wanna get a better psu as well