Forcing system upgrade despite "Battery too low"

Question

I have a 2013 Nexus 7 running Android 6.0.1 which has survived a lot of physical distress (being dropped, being partially immersed in the bath one time, and an amateur screen replacement). For the last few months, the battery constantly indicates 0% charge regardless of the actual charge state.

This prevents the Android System Update process, which gives the error "Battery too low to install updates", whether or not the charger is connected.

Is it possible to force the update to proceed anyway, or to fake the battery charge level so the update can proceed?

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I've attempted to follow the steps from the first answer, but this is the result:

1. Discharge your phone fully until it turns itself off. OK

2. Turn it on again and let it turn itself off. Can't turn on again, it's completely dead.

3. Plug your phone into a charger and, without turning it on, let it charge until the on-screen or LED indicator says 100 percent. There was no screen indication. After waiting a few hours, I pressed the power button and the lock screen came on instantly as if it was asleep

4. Unplug your charger. OK

5. Turn your phone on. It's likely that the battery indicator won't say 100 percent, so plug the charger back in (leave your phone on) and continue charging until it says 100 percent on-screen as well. Battery indicator still says 0%

The tablet does not gracefully shut down when the battery is low. It just powers off instantly.

Answer 1

You could recalibrate the battery. You could try using an app or use method 1 on this AndroidPit help page:

Method 1:

• Discharge your phone fully until it turns itself off.
• Turn it on again and let it turn itself off.
• Plug your phone into a charger and, without turning it on, let it charge until the on-screen or LED indicator says 100 percent.
• Unplug your charger.
• Turn your phone on. It's likely that the battery indicator won't say 100 percent, so plug the charger back in (leave your phone on) and continue charging until it says 100 percent on-screen as well.
• Unplug your phone and restart it. If it doesn't say 100 percent, plug the charger back in until it says 100 percent on screen.
• Repeat this cycle until it says 100 percent (or as close as you think it's going to get) when you start it up without being plugged in.
• Now, let your battery discharge all the way down to 0 percent and let your phone turn off again.
• Fully charge the battery one more time without interruption and you should have reset the Android system's battery percentage.

Don't do this too often, though, as it may reduce the battery's lifetime.