Answer to "My MacBook won't boot, no start chime, just the DVD spinning sound."Possibly a bad motherboard. This happened to my 2008 MacBook in 2015. Most likely caused by a faulty battery that expanded and pressed against the hardware for several years before I realized I should remove it. I had to get a new computer when that MB refused to boot up, but the hard drive was still fine, so I was able to get all of my files transferred over and didn’t lose anything.
Answer to "My MacBook won't boot, no start chime, just the DVD spinning sound."Try this simple trick first - it worked for me! Hold down the eject button while you push power to restart. Thanks, Tomas Jones!