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The very first step I would take is to disassemble your Fire HD. Use [guide|152197|this guide] to at least get you into your Fire HD. Take a careful and close look at all components and connectors. Truly assess the damage. Look for major corrosion, evaluate the pins in the connectors, etc,. Take a look at all the connectors as well as cable ends. You will have to remove all the EMI shields from the main board. If you do not remove the shields, you are not cleaning the board. Once you get the gross contamination cleaned, use 90%+ isopropyl alcohol and clean your parts some more. For a proper cleaning, use [guide|5825|this guide.] It was written for an Apple iPhone 3G but it is still pertinent to your device as well. I can not stress the importance of a good cleaning enough, so do it over and over while replacing the alcohol after each cleaning. Do not use compressed air for the cleaning since that can drive liquid as well as corrosion particles into areas that will cause trouble later. Do not use drinking water, if you need to use water, use sterile water. Also, you do not need to leave it to dry for a day. Isopropyl alcohol in higher concentrations will evaporate quickly and dissipate the water. The importance here is the cleaning. It would, of course, be best to get it professionally cleaned with an ultrasonic cleaner. Do not forget to replace the battery. This is a must and not an option. It will fail if you do not take care of it now. After that, reassemble your Fire HD and re-evaluate.