The 17" will boot from the smaller power supply if you have a charged battery but not without it, that's why you needed the 85 watt. This machine is just beyond the four year limit Apple set on the Nvidia issue but is still repairing some if you get the right consultant and have a silver tongue. Discount all results you had with the lower power supply and rerun them now that you have enough power to boot and let us know your results.