From what you describe it sounds like the computer is fully discharged and not accepting any new power connections.  In some cases resetting the SMC will cause it to work again - which is done via the following process:

  1. Plug in the USB-C power adapter
  2. Press (and hold) Shift-Control-Option on the left side of the built-in/laptop keyboard, then press the power button at the same time. Hold these keys and the power button for 10 seconds. (If you have a MacBook Pro with Touch ID, the Touch ID button is also the power button.)
  3. Release all keys
  4. Press the power button again to turn on your Mac

Video tutorial: