Hi @thatzlyfe ,
You’ve got nothing to lose by cleaning it using Isopropyl Alcohol 90%+ as it will not get better by itself.
Do not use “rubbing alcohol” as it is usually <70% IPA, can contain scents and is generally not as effective as purer IPA. If you have to use the rubbing alcohol check the label to verify the amount of IPA
It is better that you don’t try charging it or turning it on anymore and that you disconnect / remove the battery as soon as possible to limit any further damage caused by the corrosive effect of the impurities in the water, electricity and the electronic components combining. Unfortunately the Power button on a phone is not a power isolating button and there is always power available at various points on the systemboard
Here’s a link to the ifixit Xiaomi Mi 9 repair guides which may help. Also remember to unplug any flex cable connections on the systemboard and clean the ends of the cable and the connectors with IPA as well.
Here’s a link that may also help.
Electronics Water Damage.
If all this seems too daunting contact a reputable, professional mobile phone repair service, experienced in liquid damage repair and ask for a quote. The better ones who will try to fix it will have better equipment e.g. ultrasonic bath etc than the regular repairers or DIY’s.
If you decide to get it fixed or try to fix it yourself, do it sooner than later