Powering Up the Waterlogged Nexus 5X

After waiting overnight for the re-cleaned parts to dry, I reassembled the phone and pressed power. The lack of response was no surprise. I then plugged the phone into the charger and was very encouraged to see the screen light up with the depleted battery icon. This tells me the some of the phone made it through the ordeal in at least partial working order.

But after a few hours, the situation did not improve. So I took the phone apart again to take a closer look at the battery. When I first took the phone apart to soak in distilled water, I measured the voltage across the connector terminals and got 3.0 volts. It was lower than healthy for a lithium battery but not necessarily fatal. I measured it now - after charging for several hours - and it read zero.

So, that's not good.

I thought the battery cell might be dead, so I got another one to test my hypothesis. I wanted the connector from the existing battery so I cut apart the plastic wrap to extract it. I was surprised to find that there's a tiny circuit board inside. I'm not sure what that circuit board does... but looking at its current condition, it's not doing that job anymore. Since I didn't know it was there, it didn't receive the water + alcohol cleaning treatment received by the rest of the phone electronics. It has been under attack by swimming pool chemicals for the past few days.

Well, I wanted the connector, and now I can access the connector. Let's use it to wire up the lithium cell straight up. There were four soldering contacts on the connector, two with large conductors and two with small conductors. The two large ones were helpfully labeled "V+" and "V-" so that's how I soldered the lithium cell.

And it worked! This setup was sufficient to get into the Android OS. Now that the screen is showing more than the "depleted battery" icon, I could see that it was damaged in this adventure. Thankfully it was still legible, and the touchscreen still worked, so I could run the phone for about 40 minutes. Long enough to access the multi-factor authentication app so I could transfer my MFA security to another phone.

Since the phone appears to be running, I ordered a proper replacement battery. I don't know if the corroded battery circuit board did anything bad to the rest of the phone. The charging circuit may have been damaged trying to charge a zero volt battery for hours. I'm going to see how the phone works with the replacement battery before spending money to address the damaged screen.