I had a similar issue. My macbook crashed, nothing would restart it. I did the NVRAM reset multiple times, it seemed like it did not work, though I could hear the chime on startup and when i would fiddle with the volume control would hear the "pluck pluck pluck" sound. Then I shut the notebook, reopened it and VOILA it worked! Was so thrilled, I thought this Macbook had bitten the dust!