PC boot failure with flashing power button and blue screen crash

Recently I have been unable to launch my PC 3/4 times. I press the power button and it rapidly blinks for about ten seconds, before slowly blinking once every two seconds. There is no display on my screen and the LED of my keyboard/mouse do not light up as usual.

I have tried:

• RAM including changing slots, booting with one stick at a time

• Reseating GPU

• Cleaning inside of case

After I managed to get it to launch, it worked fine for a day or two, but then I have had several blue screen crashes with the error message ‘your device ran into a problem and needs to restart’ with ‘kernel security check failure.’ These crashes came after my display became distorted while watching a Youtube video. I now cannot even launch my PC and am back to the first step, so software diagnostics are out of the question.

Any advice is appreciated.

Motherboard: PRIME B760-PLUS D4
90MB1CW0-M0EAY0