My phone redmi note 6 pro was dead because of water. So what I do?

Hi,

As you know water and electronics and electricity are not a good mix.

The impurities in the water causes corrosion and provides circuit paths for the electricity which were not in the phone's operating design and could damage the components.

First do not turn on or attempt to turn on your phone and then you need to remove or disconnect the battery as soon as possible from the phone to minimize any further damage.

After this you need to dis-assemble the rest of the phone and clean all the affected parts using Isopropyl Alcohol 90%+ (available at electronics parts stores) to remove all traces of corrosion and water. Do not use "rubbing alcohol" as in some cases this is only 70% IPA or less, can contain scents and is not as effective. If you do have to use it, check the label to verify the amount of IPA, the higher the % the better.

Here is a link that describes the process.

Electronics Water Damage

As always with electronics, especially surface mounted PCBs be gentle when handling and especially when brushing away the corrosion. You do not want to remove any components from the board.

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

Here is a link to a video that shows how to replace the screen in your phone. I realize that this is not the problem but it should help you to gain access to the internal components, especially the battery

If this process seems too daunting, take your phone to a reputable, professional phone 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.