Answer to: backlight is out but still works finethere is a small black capacitor that has black epoxy on the upper left side of the charger port, that one need to be replaced. but it's very small and very difficult to do it. you may end up damage the logicboard. I Suggest to use it as ipod only, not for any game anymore.
Answer to: Not booting up properly?don't try to turn it on anymore, please open it and clean up the stain, and hope there is no blowed up IC/SMT Capacitor or inductor(this one is blew up since you can't charge the battery anymore). and hole the LCD cable didn't short out, otherwise you really need a new logicboard and also new LED screen, and also new LVDS cable. or otherwise clean it up until there is no other trace of liquid and ask for flat rate repair, that will cost you $300. other than that, you only can use the SATA super drive, the shell and the hardrive, battery, and also the glossy Glass with MacBook Pro logo on it.
Answer to: Heatsink doesn't make contact with processorsUse 0.4mm Thermal pad. and you good to go.