Pc won't start

Hi @mabez

The impurities in 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 is ongoing until it is completely cleaned away

First do not try to charge or to turn on your laptop and then disconnect and remove the battery as soon as possible from the laptop to minimize any further damage.

Then you need to dis-assemble 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 and water. If possible do not use "rubbing alcohol" as in some cases this is only 70% IPA or less, can contain additives which may leave conductive residues and is not as effective. If you do have to use it check the label to verify the amount of IPA. The higher the percentage of IPA the better

Here is a link that describes what happens 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. The ends of any flex cables and their connectors need to be cleaned as well

Hopefully after you have done all this the laptop might possibly work correctly again.

Here is the ifixit HP EliteBook 840 G7 guide that may help. Also here's the maintenance and service guide, taken from the HP support webpage for the laptop. The service guide is useful if you have to replace any parts as it has the HP part numbers for all the removable parts in the laptop, making them easier to find if any need to be replaced.

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. If you decide to do this, do it sooner than later.