My MacBook Pro is charged and it won't turn on

Try an SMC Reset if you have an Intel Mac.

Let the laptop charge longer before attempting to power on the laptop.

If you have a Magsafe model does the Magsafe LED light up?

If you have a USB-C model, then try using the other USB-C port. Try rotating the USB-C connector 180 degrees upside down (I know it sounds crazy). Try it both at the laptop end and at the power brick, but only one at a time to see if it makes a difference). Do you hear the "ding" sound after a few minutes of connecting the USB-C charger?

Regardless of model, unplug the charger from the electrical outlet for a minute to reset the charger's internal circuitry.

See if your laptop qualifies for either of these free Apple repair programs:

https://appleinsider.com/articles/19/06/30/apple-conducting-free-but-limited-logic-board-swaps-for-2018-macbook-airs

https://support.apple.com/13inch-macbookpro-battery-replacement

https://support.apple.com/13-inch-macbook-pro-display-backlight-service

If the battery in your 2016 or 2017 MacBook Pro won't charge past 1% - Apple Support

FYI, here is the current list of the publicly acknowledged free repair programs for various Apple products (some products have multiple programs available):

https://support.apple.com/service-programs

Regardless you will likely need to have Apple or an Apple Authorized Service Provider examine the laptop to provide you with a repair estimate.