MacBook will not turn on after charge was lost

When an Apple laptop's battery is completely drained it can be difficult to charge the battery and to even power on the laptop as the laptop can get into a weird state. As soon as an Apple laptop's battery is drained you should begin charging it immediately if possible, otherwise you can encounter this problem.

With the USB-C Apple laptops things can get even more complicated.

First try an SMC Reset.

Second try letting the laptop charge for several hours to see if the battery will take a charge and power on.

If you have a USB-C Apple laptop, then try using another USB-C port especially on the other side of the laptop if you have the four port model. You can also try rotating the connector of the charging cable 180 degrees upside down (I know it sounds crazy, but it can make a difference if the port is half bad).

Make sure you charger and cables and connectors are in good condition and make sure you are using the correct size charger (or larger).

Apple Portables: Troubleshooting MagSafe adapters - Apple Support

If your USB-C power adapter isn't charging your Mac notebook - Apple Support

Depending on the exact model of the laptop it may be possible to disconnect the battery and attempt to power on the laptop while the battery is disconnected. If the laptop powers on, then you can reconnect the battery while the laptop is still powered on. Let the laptop charge at least 10% before powering off the laptop or disconnecting the charger or you risk permanent damage to the battery. You must be extremely careful not to have the exposed electronics make contact with any metallic or conductive item or surface. I do not recommend doing this on a USB-C Apple laptop as it is very easy to damage the laptop with its very fragile cables plus it is very difficult to remove & reinstall the Bottom Case.

You may need to have Apple or an Apple Authorized Service Provider examine your laptop.