Nexus 7 (2012) won't charge or start after a series of problems

Question

A year or so ago, I bought an old Nexus 7 that was very slightly used (I took it off my girlfriend's hands). Everything worked fine, but I barely ever used it.

Two days ago I broke it back out. I charged the battery to full but never ran anything. The next day, I opened it up again and noticed that there was an update - 5.1.1. Not researching beforehand, I went ahead and tapped the notification, and then the problems started flooding in.

First, the tablet became locked in the loading animation after the Google logo. I let it do this overnight just in case, and it was still stuck in the morning. So I held the power button and volume button until it turned off and tried to reboot it.

At this point, it booted to a 'No command' screen. I did a factory reset from here, and rebooted. Now the tablet became stuck in a reboot loop of the Google logo.

After some research, I flashed it back to version 4.4. Everything worked fine with the fastboot and everything was working great. I ran a few updates from the tablet and got to version 4.4.4. Again, it loaded fine.

I tapped the envelope icon in the top-left corner to view my e-mails. As I was reading the first one, the screen froze. I let it sit for a few minutes and it was still frozen. So again, I powered off by using the power and volume button. My battery was around 30% at this point.

Now the tablet shows absolutely no signs of life. I have tried holding the buttons with all of the combinations that are online, I have tried doing combinations of buttons while plugging/unplugging the charger. I have tried using a regular micro-usb charger as well as a 2A charger. I have tried reseating the battery. NOTHING has worked. The tablet shows NO signs of life - no flashing, blanks, anything at all.

What else can I possibly do?

Answer 1

Looking at your issue related to battery and charging (which may not be the sole cause- I am not familiar with Nexus devices)

• Since you barely used it for an year, it would not have been charged either and the battery could have discharged to very low levels. Li Ion batteries have a protection circuit that kicks in when the discharge falls below a certain level. It requires certain current to be applied to it before charging can happen. This is called "Boosting". How to awaken sleeping Li-ion explains it. Fix: Nexus 7 Refusing to Charge, Try This Trick mentions steps getting into the bootloader to revive it

1. Plug-in your dead N7 to a wall charger. (Jump immediately to step 2.)
2. Immediately after plugging it in, press Volume Down and Power at the same time.
3. Once in the bootloader menu, use Volume Down until you see “Power Off Device.”
4. Choose that option with the Power button.
5. Once your device is off, unplug the charger and then plug it back into the device.
6. You should now see the battery meter with your device returning to life.

• You could also try to change the charging cables- I would suggest is to use a 20/22 AWG cable for charging (if you don't want to buy, look for a short thick charging cable-it may help). See answer here for my details. Nexus 7 is more choosy: It will stop charging if voltage levels drop and resistance comes into play again. Google Nexus 7 Charging goes into details and says

Nexus 7 will stop charging if the input voltage is less than the internal battery voltage plus 0.2 volts.

• There are other drastic methods, which you could try if you are comfortable, involving jump starting

Answer 2

First of all, relax. You didn't break it.
Absolute worst case scenario is that your battery is completely dead.

If you want to do this the easy way, you can always unclip the back of the Nexus 7(just slide a guitar pick in between the screen-half and the rear-half), unplug the battery (carefully) and either find a way to charge it (put it in another Nexus 7, etc.), or replace with a battery that works.

PS. This is literally as bad as it gets in terms of how much damage you can actually do by carelessly flashing ROMs on an Android: A situation where the device really appears to be broken. Don't ask non-technical friends what they think, and resist any temptation to break it all the way. Charge the battery to 100% before flashing and you'll never have this problem again.

Answer 3

​I have a Nexus 7 which has not been charging over 20%. Today I put it in the oven at 50C for 30 mins then took it out and knocked it sharply on the bench a few times. After 3 hours on charged now have 100% charge