So after having opened up the laptop after years of use for cleaning and re-pasting the cpu and gpu, my laptop won't start at all. The battery died a while ago so I've been using it without one without any problems prior to the disassembly. After doing so, the macbook won't do anything upon pressing the power button. The magsafe adapter light is green but it just doesn't seem to want to start anymore. It actually booted once after many tries but never again. I've tried almost everything like resetting the pram, smc, re-seated the airport card, made sure the ram was seated correctly etc... What else can I do? I'm reluctant to take it for repair since it is no longer worth the cost of inspection in my opinion. Thanks!