Hi,
''The water causes corrosion and provides circuit paths for the electricity which were not in the laptop’s operating design and could damage the components. The corrosion starts immediately and doesn’t stop until it has been properly cleaned away.''
'''Do not try to charge or to turn on the laptop''' and then '''remove the battery as soon as possible''' so as to minimize any further problems.
Next you need to disassemble the rest of the laptop and clean ''all the affected parts'' using '''Isopropyl Alcohol 99%+''' (available at electronics parts stores) to remove all traces of corrosion. Do not use "rubbing alcohol" as in some cases this is only 70% IPA or less, can contain additives and is not as effective. If you do have to use it, check the label to verify the amount of IPA. The higher the concentration (%) of IPA the better
Here is a link that describes the process. [[Electronics Water Damage]]
As always with electronics, especially surface mounted pcb, be gentle when handling and especially when brushing away the corrosion. You do not want to remove any components from the board. Also remove any shields that may be covering some components and clean there as the water may have got in under them as well. The ends of any cables and the connectors need to be cleaned as well.
Hopefully after you have done all this time the laptop ''might'' possibly work correctly again.
Here is the [http://h10032.www1.hp.com/ctg/Manual/c05357618|maintenance and service guide] for the laptop that may help. It details the necessary pre-requisite steps and then the procedure to remove all the components etc that will make it easier to clean etc.
Also on p.21 Item #3 you will find the part numbers for the various display panels that are used in the laptop. Search online using the part number ''only,'' that is appropriate to your particular model variant, to get suppliers of the part. Usually the part number is printed somewhere on the back of the original panel if you wish to verify that you are ordering the correct one.
If this process seems too daunting, take your laptop to a reputable, professional laptop repair service, experienced in liquid damage repair and ask for a quote for a repair.