[Xperia Tablet Z Q&A, Help & Troubleshooting] Wonka_Vision:
Hi everyone - I'm having problems getting my device to turn on properly, and I can't seem to find a solution anywhere. I bought the SGP311, and everything was going great with it until like 2 weeks ago when it just wouldn't turn on properly. The red light on the side next to the power button was on, and I had to mess with the buttons in different combinations (I think while the device was plugged in) in order to get it to turn on properly. It was not out of charge or low on charge at this point, and I had never tried to alter the device in any way prior to this.

I encountered the same problem yesterday where the device wouldn't turn on, and I couldn't get it to turn on no matter what I tried. I thought that it might be a problem with the OS, so I used FlashTool to install a custom FTF file (a Japanese one), and it wouldn't boot up after. I plugged it directly into a power source (not through my computer), and eventually the device turned on and I was able to go through setup, etc.

The OS had a lot of Japanese text, even though I had selected English, so I thought I'd wipe the tablet and update the OS using the Sony Update Service tool, which successfully detected the device and did a factory reset and software update after I put the device in flash mode. The app then told me to unplug the tablet and power it on, but nothing happens when I hold the power button down.

Here's what happens when I try to do different button combinations:

With the device plugged into the power (ie into the wall):

The red light comes on and stays on.

If I hold the power button only for a few seconds and then let go, nothing happens (red light stays on).

Hold up on the volume and hold power, the white light flashes once and then nothing happens (red light is off and stays off).

Hold up on volume and wait for the 3 white light flashes then let go gives me back the right light, which then stays on.

When the device is unplugged:

the red light remains on.

Holding the power button doesn't do anything (red light remains on).

Holding volume up and power causes the white light to blink once and then the red light turns off (as before).

Holding volume up and waiting for the three white flashes does not return the red light (unlike before), but then plugging the device back into the wall makes the red light return.

When the device is plugged into my laptop:

Red light comes on and remains on.

Holding up and power causes the white light to flash once and then the device actually booted, and I went through the setup (but it was still in Japanese, for some reason). When I power off the device, I am unable to power it back on by holding the power button. I am unable to turn it back on after by using the method (holding the volume up and pressing power when plugged into my computer). It just stays off.

Holding power up for long enough to cause the 3 white blinks returns me to the red light.

My device is charged through all of this (>80%), so I don't think it's a battery thing, but boot up can't just be happening randomly. When the device actually does turn on, everything functions normally. It's only when it's turned off that I can't get it back on without dumb luck each and every time.

Has anyone encountered anything like this? It's really driving me nuts. Please let me know if I need to clarify things more. I could really use help on this because I don't think I possess the cranial capacity to solve this on my own.

Thanks!