Chosen Solution
The green light on the Magsafe adapter comes on, but the computer will not power on (no fan, no anything). I’ve tried the reset button combination. Nothing. Could it be the Magsafe board? Logic board? I have both parts from a donor computer that I’m 99% sure should be good (but I can’t check). Is there anything else it’s likely to be? I’ve got the case opened up with the battery removed and nothing looks disconnected or obviously damaged to my untrained eye.
If you haven’t already, try a separate known-good MagSafe charger. If that doesn’t work try the next steps. Try an SMC bypass. With the battery and MagSafe charger disconnected, hold the power button for 10 seconds. Then attach the MagSafe charger while still holding the power button. Continue to hold for another 10 seconds and then release the power button. The will force the machine to power on regardless of the SMC sensors on the logic board. If it requires an SMC bypass to power on, you most likely have a damaged or faulty logic board. If it still doesn’t come on with an SMC bypass, there may be a problem with your MagSafe board. Inspect the pins in the MagSafe port. Are there signs of burnt pins? If so the component may have failed. You can also try cleaning the MagSafe port with a Q-tip and isopropyl alcohol. You can also use a multimeter to read the voltage being passed by the MagSafe board to verify it is the correct value. I hope this helps!
