The Lights On The Front Of Your Computer Turn On or Flash, But Nothing Else Happens.
Usually this is indicative of a failed power supply. In my experience, 80% of the time that was the case, 19% of the time it was a failed motherboard, and 1 time (not 1%, just 1) it was a rare error involving the front panel controller board. Most computers don't have extensive controller boards in the front panel but Dell seems to favor them heavily. To troubleshoot a failed Power Supply or Motherboard please refer to the previous installments of this series.
Your Computer Emits Loud Beeps or Tones
These noises you are hearing are called Post Error Codes or Post Error Beep Codes. Different combinations of long and short tones indicate different potential problems. Most computers will emit one short beep when they "pass post". Post stands for Power On Self Test, and is a series of checks your computer does on itself to make sure it is working properly. A single, short beep is the "All Clear" message.
The interpretation of the Beep Code you hear is entirely dependant upon your computers BIOS or manufacturer. If you do not know what BIOS type your computer is using, call your computer's manufacturer and ask. If they can't tell you, then you will probably have to do an internet search of your motherboard's model number, which is usually painted on your motherboard.
The interpretations for all the different motherboards is far too long of a list for me to disclose here, but this website has a very good and complete list.