It's a common gaffe by owners so don't feel bad. Many monitors do that if there is no signal.

Also, many desktops start the fans at top speed until they boot. It's a safety decision to keep a crashed machine from overheating. (still not getting down to anything wrong yet!)

As to the battery, what Volts did it read? Or try another. You left out the exact age of the machine, battery and model details. Be sure to retry without any USB devices plugged in.