I have the exact same model of piano. I am able to get it fixed. It took me about 6 hours. The keys would not return to its up position after pressing on it. It turns out the white plastic that holding the weight of each key has expanded over time. The aluminum rod that goes through each weight is getting too tight for the weight to move (rotate) freely. Also, the expended white plastic is pushing against the side of the black case that holds the weight and the rod together.

To fix the issue, I did the following:

1. Take the keyboard assembly out of the cabin.
2. Remove a black slotted case at the bottom side of the keyboard assembly that holds the weight and the aluminum rod. (I started from the right where the case holds only 4 keys.) In order to do that, remove the keys from the assembly first. (You have to first remove the screw, a metal plate, and a black thin plastic thing that holds the keys in the locked position at the back of the assembly, Then push the key toward the back of the assembly to unlock each key and lift it out of the assembly.
3. With a long screw driver (or a unsharpened pencil), I push the aluminum rod out while wiggling (rotating) the black case back and forth so that the rod would rotate a little bit.
4. I took all the weight out of the case and put them all one by one back on the rod in the correct order for easier assembly later.
5. With the weights on the rod but without the case, I rotate the rod until the weights no longer bind to the rod. (I later discovered that it works good when I use an electric drill to hold the rod and spin it)
6. Test each weight to make sure it can swing freely on the rod.
7. Remove each weight from the rod and insert it back to the case. Check and see if any weight is binding to the wall of the slot. It should be able to slide in and out freely to each slot. If it is binding to the side, use a piece of sandpaper (150 grid works good) to sand the side of the white plastic where it is touching the wall of the slot a little bit until it can be inserted back to the case smoothly. Remember to clean (vacuum) the dust out before putting it back to the slot.
8. Insert the rod back to the case and carefully feed it thru each weight.
9. Test to make sure each weight can now swing freely.
10. Put the assembled black case back to the keyboard assembly.
11. Repeat steps 2 to 10 for each black case that has keys that won't return to the up position.

Hi @denniswint31196,

Has the phone's LDI changed colour to red? If so then there may be more damage than what is obvious to the eye.

Did you disconnect, check (and clean) the display flex cable end and associated systemboard connector in case water got in there? Also the water may have got under any shields that are covering some components. Best cleaned using Isoproyl Alcohol 99%+. Also make sure that when cleaning that the battery is disconnected from the systemboard, until the alcohol has fully evaporated.

Here's the No Display troubleshooting flowchart from the service manual that may help. Also images (both enlarged and normal size) showing the location of some of the components shown in the flowchart

(click on images to enlarge)

@debrutal

Here's a teardown video that may help.

It looks like the LDI #1 marked in your image is a spacer of some kind because at 3:00 minutes into the video it is seen and it is the same colour as shown in your image.

As the LDI#2 in your image, near the SIM reader (also seen at 3 minutes into the video), appears to be OK, water didn't enter through that way but this doesn't mean that it didn't get in anywhere else.

The cable ends shown in the other image you posted may be corroded or it could just be the camera angle and the light but looking at 3:39 minutes into the video they seem very bright and silvery.

I would check the cable connector underside (not shown in your image) and also the systemboard connector for the cable to see if the pins look corroded or not.

As for U5002, no doubt you'll need microsoldering experience and tools if you need to replace it. Unfortunately the service manual I have has no parts list so hopefully some info is printed on U5002 to help identify exactly what it is, besides the fact that it is a PMIC - Power Management IC