Engine turns over but wont start?

My car was towed to a garage because I had somewhat the same problem, we've checked everything else, but the garage guy put it through some diagnostic thing and the outcomes was some "computer chip re-boot" who knows what that was but anyway he provided me a note in case it ever happens again and it did at least several times. (Saved me a few times already)
The note reads:
Turn your key to on position for 10 minutes.(Do not start the engine), your security light should be blinking on and off and once it goes out, turn your key to off for 10 seconds and back to on again to see if your security light blinking, if not then turn your engine. If it continues to blink repeat the 10 minute process again. But if that doesn't work for you I guess you have other car issues. GOOD LUCK!