MacBook won't boot or charge

If the machine won't power on and an SMC reset doesn't help, the first step would be to try a separate known-good charger. If that doesn't work, you will need to take further diagnostic steps and will most likely need to open the machine. It's possible the battery is failing, or there may be damage internally to the USB-C port or the main logic board. If you can get the machine to power on for any length of time, download the coconutBattery application and take a look at the battery health. If the cycle count is greater than 1000 or the design capacity percentage is less than 70% or the status of the battery is anything other than Good you may have a bad battery.