[Nexus 7 Q&A, Help & Troubleshooting] Huku6600:
Hi guys. Issue #3 (from the OP) here.

Recently my tablet (Nexus 7, 2012) started to reboot randomly. Sometimes more than once per day. I thought this might be due to the reduction of free disk space. It was decreased to less than 1 GB. Freed another 2 GB. This seemed to help.

Until a day - or two. Tablet then turned off but does not restart. I turned it on the usual way by pressing the power button for about 5 seconds. After a few hours it turns itself off again. I turned it on back without difficulty. I left it plugged into the charger for the night. The next morning I found the tablet off.

5 seconds of pressing the power button does not work.

After disconnecting the power cable and reconnecting it – no battery animation on screen.

As this was happening for the first time, it was time to look for a solution on the web. (Maybe it's time to clarify that the tablet worked fine for over a year and a half, it hasn’t been dropped or got wet, and has stock Android 4.2. It’s not rooted. No problems with the battery so far.)

Here is a list of tested suggestions for solution:

Long pressing of the power button for more than 30 seconds;

Pressing volume up + power button for about 5, 30, 60 seconds;

Pressing volume down + power button for about 5, 30, 60 seconds;

Pressing volume up + volume down + power button for about 5, 30, 60 seconds;

Disconnecting the power cable, wait a bit and reattach and immediately pressing the power button (power button + volume up/down/both) for about 5, 30, 60 seconds;

Using another cable and/or charger…

All this to no avail.

I had some concerns to open the back cover but all this led to the conclusion that the battery is disconnected.

It wasn’t. There was no space between the battery and the casing also.

I disconnected the battery for a while. I don’t have a device for measuring voltage, but I found a LED and it lit up quite brightly. So the battery was charged. I reconnected it back, closed the back cover and tested again the above combinations. Nothing worked. Still no battery animation on screen when connected to charger.

For a moment I thought that the display does not work. But if the tablet is starting normally and the screen just doesn’t work, I'd be able to hear the sounds of the notifications after its launch. There wasn’t any sound also.

Until now I had not connected the tablet to my laptop, as it was much more convenient to me to transfer files between them through ftp. I connected the tablet but the computer did not recognize it. “USB Device Not Recognized”.

However, a ray of hope. At least the laptop recognized that there is "some kind of" device attached. Had only to install the necessary drivers. (Around that time I must have been reconciled with the probability to come to a factory reset.)

Any "how to" that I found was related to ADB, so I downloaded and installed Android SDK along with the drivers… “USB Device Not Recognized”

Downloaded USB drivers from Asus… “USB Device Not Recognized”

Then I came across [ADB / FB / APX Driver] Universal Naked Driver 0.72 here at xda-developers.com. Still “USB Device Not Recognized”, still exclamation mark in a yellow circle in front of “Google Nexus 7 ADB Interface” and “Google Nexus 7 BootLoader Interface” but there is one difference now:

If, while the tablet is connected to the laptop, I press and hold the power button for about 10 seconds, the Device Manager refreshes and "Asus Transformer Prime APX Interface" remains active until I disconnect the tablet. There is no difference if I use only the power button or a combination of the above and in the duration of the button pressing more than 10 seconds.

“adb devices” command returns blank list in both cases: with or without APX interface recognized.

And as any "how to" that I could find, inevitably leads to something like "Step #N: Reboot tablet by holding down volume down and power buttons, you’ll see bootloader screen on the tablet…" I can’t continue from where I am stuck now. There’s no way for me to see anything on the screen since my tablet turned off by itself a few days ago.

Any suggestions what can be done from this point on?