MacBook doesn't boot: no chime/fan, only hard drive & DVD sound

Hi!

I've got a Macbook that completely stopped working. When I turn it on, only the hard drive makes a faint spinning noise. The fan remains still and there's no status light. I've inserted a DVD and now that starts spinning as well. I've tried a PRAM reset, SMC reset, disconnecting the battery, using a different charger, disconnecting the hard drive and playing with the bars of RAM. An answer I found on iFixit said to hold down the power button while connecting the charger for 10 seconds and then quickly releasing and pressing the power button again. Doing that, the fan spins at top speed but the Mac still doesn't chime or turn on the screen. I'm running out of ideas, any suggestion?