If you are having trouble with your ESC turning on, your immediate thought might go straight to thinking that you have a dead ESC. But before replacing your entire ESC try one extra thing to be absolutely sure it's not just a bad power button.
Step 1: Disconnect your power button
Disconnect your power button and set it aside for now.
Step 2: Locate the power button pins
Inside of the power button port, there are 4 metal pins.
Step 3: Short Pin 1 and 2 labeled POW and GND
With a screw driver, carefully place the tip of your screw driver in between the 1st and 2nd pin to purposely short the connection. This will act like a button press.
If your ESC beeps and lights come on, that is great news! You'd just need to replace your power button.
If nothing happens, there is a good chance that a replacement ESC is needed.