My dell latitude 7290 won't boot after falling into water

Hi @williams93090

Allowing it to dry may not have been enough.

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

Even though the laptop may have been turned off, there's always power present on the motherboard. The laptop's Power button is not a power isolating switch. Its function is to signal the user's intentions to the BIOS or OS

First do not try to charge or to turn on your laptop until it has been cleaned properly and then 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 device 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 describes what happens. Electronics Water Damage

Here is the owner manual for the laptop. Go to p.14 to view the procedure to disconnect/remove the battery. Then follow the manual to remove the components that can be removed to thoroughly clean and dry everything else.

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. Remove the shields that may be covering some components as the water may have got in under there. 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.

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.