PSX 7700

Hello everyone,

I’m having a problem with my PSX. As soon as I plug in the power supply, the fan spins briefly and then it’s basically dead. No LEDs light up at all.
There isn’t a hard drive installed at the moment because I’m still waiting for my ATA Express. However, the console should at least boot or show the startup logo, but absolutely nothing happens.
I can also rule out the power supply because I’ve already installed a RE-PSX power supply.
What could be causing this issue? I’m honestly running out of ideas and getting pretty desperate.