Thermal paste replace gone wrong

I tried replacing the thermal paste to hopefully fix some of the noise from the fan and overheating from a few games. in doing so I accidentally punctured one of the ribbon cables breaking one pin connection to what seems like the optical drive which I thought would be okay since I dont use discs hardly any more. After putting everything back together it “starts”, flashes the light a second or two and then shuts off. I've looked and some people have said this could be the power supply, so I'm wondering if the ribbon cable is causing a fault read and stopping the system from initiating or if I managed to mess up the power supply somehow

Hoping to get an answer because one is drastically cheaper to fix than the other