First things first, TURN IT OFF and UNPLUG THE MAINS ADAPTER.
Obvisously, until you open up the laptop there is no way of knowing what kind of damage has been done and it's not always possible to repair a water damaged laptop, especially if it has been powered on after it has dried without it being professionally cleaned first...
The flowchart below details how to professionally clean a motherboard etc.
If the spill has recently occurred then grab a paper towel and dab the motherboard to remove the remaining liquid and then follow the flowchart below.
Required Items/Tools:
- Isopropyl Alcohol and/or Water
- Nylon Brush to do the cleaning with (a cheap toothbrush is ideal)
- If available, a hot air rework station
TOP TIP: Use liquid Rosin Flux to prevent any further damage to any pins (on integrated circuits like SIO/Chipset) as if the pins are covered in Rosin then oxidisation (i.e. rusting) cannot occur.
Apply liquid Rosin Flux to affected chips/pins and then use hot air to remove the IPA in the liquid flux to just a leave a protective layer of Rosin on the pins.