Switch off the laptop Tip it in the opposite direction of the liquid ingress to remove as much liquid as possible, use a kitchen towel to mop up the excess.
DO NOT switch the computer on!
It is unlikely you need a new motherboard but you will need to get it to us quickly (before corrosion sets in).
There is a strong chance that you will not lose any of your important documents and photos.
After a liquid damage event, disconnect the power supply immediately by unplugging the mains and disconnect the battery where possible.