yashsingh1/xdaforums huggingface dataset:
[Nexus 7 Q&A, Help & Troubleshooting] bftb0:
That is only the case when there is some form of voltage regulation taking place; if the voltage impressed upon the battery terminals is allowed to grow arbitrarily large, so will the currents through the battery. For instance, if you were to charge the device normally through the USB port, as opposed to the bare terminals of the battery. In that configuration the SMB347 (USB interface) chip is performing voltage regulation pecisely to prevent an overcurrent charging condition.

That is why you see the TI BQ2754 chip reporting a voltage across the battery that is always less than 5V (the USB Standard DC supply voltage) when you are charging the tablet, and which rises slowly as the battery charges ... but never reaches 5v, even when the battery is fully charged and zero net current is being "regulated" into the battery.

If that were not the case - for instance if the battery pack itself had a built in regulator, then you would see the TI BQ2754 chip always reporting approximately 5V (minus droop of the charger) any time you were plugged in to a charger. That would be the case if the battery pack were performing regulation itself, as there would be no need for secondary regulation. But that's not what it actually observed.

You are correct though that when a regulator is in place (charging through the USB port) you might be able to use a 12v, 2A USB charger, and the battery would charge at exactly the same rate as if using a 5V, 2A charger. This is only advisable if the regulator is spec'ed for that overvoltage condition. Unfortunately, SMB does not make their data sheets public, so better safe than sorry!
[Nexus 7 Q&A, Help & Troubleshooting] quick_:
Anyone know what else I can try?

My Nexus 7 was locked up on the clock, (while charging) and I have never been able to turn it on again.

I have tried charging it for 1 min, 5 min, 100000mins (factory charger, dock pogo charger, usb, other chargers) Holding all combinations of the power buttons and volume buttons for 1+ minutes.

I have take it apart checked the battery cable, which was fully attached tightly. Unplugged it, waited 10-15mins plugged it back in put the cover back on and still nothing.

I tested the battery with a volt-meter and it shows FULLY charged 3.75v.

Still will not power on, screen never flashes, no charging icon nothing...

EDIT:

Just noticed that when plugged into USB on a windows PC, in device manager I see APX under "Other Devices" and it seems that the power button does work since if I hold it for 10 secs it will disappear from device manager and then come back with the "APX"....

Any ideas?
[Nexus 7 Q&A, Help & Troubleshooting] Huku6600:
After the same symptoms I contacted the Google support. They put me on the phone with the ASUS support. The ASUS guy told me that I have to send the device by mail and it will be diagnosed for free, but I have to go through the RMA process and subsequent repairs will be paid by me. (My warranty has expired a month ago.)

Based on the diagnostics, he assured me that the possible failures are few and the prices for their repair are as follows (including delivery costs):

* Main board replacement - $203

* Battery replacement - $53

* Flash memory replacement - $40

I was told that after the diagnostics I will get an email with a description of the exact damage, and the cost of repair, and I will have the opportunity to decide whether the device to be repaired or to be returned to me in its current state.

I suspect that the flash memory is damaged somehow. The good news is that it is replaceable (if we can believe the phone support.). If this is not the case, I am afraid that I will have a slightly expensive trencher.

Today I sent the tablet to ASUS by FedEx. We'll see what happens from here forward.
[Nexus 7 Q&A, Help & Troubleshooting] Tialis:
Hi all,

My screen broke, and I ordered a new one for replacement. I saw video tutorials on how to do so and it seemed rather easy... so I just received it and changed it. Before the change the screen was still showing everything, but no touch input was working.

After the replacement, screen wont turn on. If I connect it to my laptop it does work (I can access the internal memory) but it doesn't work the screen at all (in fact, I don't know if touch input works or not...).

I tryed all solutions written in this thread, so I am out of ideas. How do I test if the mother board is still working? How do I test if the screen is working? Is there an easy way? (I have good equipment in my work for testing)

Thank you!
[Nexus 7 Q&A, Help & Troubleshooting] zex15.design:
i had same problem with

It hapends to my NEXUS 7 tilapia becouse of kernel.

This one from pack:

"4.4 Stock Kernel with USB Tethering, 4.4 Stock Kernel with USB Tethering and Kexec Hardboot"

After reflashing factory img my nexus works normal :)
[Nexus 7 Q&A, Help & Troubleshooting] Huku6600:
Two weeks later the ASUS Service Center (4051 N. Hwy 121, Suite 100, Grapevine, TX 76051) responded:

"...Cost of repairs (all amounts are USD) – enter amounts on credit card form PRIOR to printing the form:

Parts - $ 116.00 (LCD)

Labor - $25.00

Tax**- $13.68..."

LCD?!... Dafaq?!... :confused: :eek: :silly: Really?!...

Looks like they even didn't try to turn the device on!

I replayed with an angry answer: "...do the necessary tests and only then send me a quote..."

We'll see what happens from here forward. Again. (I'm mad just now!...)
[Nexus 7 Q&A, Help & Troubleshooting] PianoThing:
Issue resolved for me last night

After OTA to 4.4.2 on both my wife and I's N7's, I installed CM 10.2 STABLE on both with LeanKernel. Right off the bat I had the very same issues you did and officially my tablet was dead as a door nail last night after sitting all day. Within 15 minutes of me troubleshooting mine, my wife's killed itself as well (also these tablets are 5 days old). I attempted battery pulls and everything to no avail, but what did work was holding down Power + Down Volume together till the tablet turned on. Worked like a charm, loaded Purity ROM with LeanKernel and it's running beautifully, power response from button is instant, haven't had one force close.

Though I have been a very avid CM user for years, I sadly will say even on stable builds, I always run into issues like this, but the without have doing it on both of our tablets with the exact same ROM, I would have guessed differently.

Best of luck to you :D
[Nexus 7 Q&A, Help & Troubleshooting] OneRing2Rule:
Dead Battery?

Okay, I've picked up a free Nexus 7 that was dead. The previous owner said it didn't charge and the cable was loose. I replaced the charging port and it did charge on a non-OEM 2.1 A charger. Powered all the way full. Did a factory reset. Promptly put it away to sell on Ebay someday. Two months later, I take it out. It's now deader than hell. No amount of button pushing, charger swapping, cable swapping will wake it up. Bought a OEM charger and cable on ebay and still nothing. Finally, lifted the back off again to check the battery. Firmly in place. But here's the kicker.

I put a meter on it and it has 1.27V on it. :eek: That's redonkulously low. When I put the charger on it, I can see the volts coming in at .5V. After two hours, I metered it again and it's at 1.27V. No change.

The battery is dead, right? Just bought one for $18 on Ebay. Hopefully, between the charging port ($31), the charger (with box and everything, $29) and the battery ($18), I'll be abler to get my money out of this. ($96)

Any thoughts on the battery. Can I shock it awake or is the thing dead?

OneRIng2Rule:cool:
[Nexus 7 Q&A, Help & Troubleshooting] alex12349:
battery level goes down then up again

bought my N7 in Feb this year, now when ever i run some app or game like candy crush etc its battery drops down by almost 20% but after sometime on idle it rise back; what's that supposed to mean?

m on stock 4.4.2
[Nexus 7 Q&A, Help & Troubleshooting] jiminsd101:
nexus 7 random shutdown

Somebody said test in safe mode. If problem goes away it was caused by an ap. Did this, found problem was caused by Weather bug.
[Nexus 7 Q&A, Help & Troubleshooting] 100012148:
Nexus 7 will not turn on

Hi,

My Nexus 7 is just over a year old and it will not turn on, i have tried all the usual stuff on the web and i still cannot get it to turn on, or show a Battery charging icon to say it is charging. The battery voltage is 3.1 vs which is okay, i am cahrging with a origonal nexus charger.

I ave tried charging for an hour, overnight, pressing the power button and the down button, no sequence of the buttons appears to work, nor does plugging out the charger and in within 10 secs and powering on, can anybody help me?

Thks Joe
[Nexus 7 Q&A, Help & Troubleshooting] quick_:
Did you try removing the back cover and unplugging the battery, then reconnect?

If you plug it into your PC do you get APX device in device manager? If so, your device is toast, corrupted bootloader, which can't be fixed without replacing the motherboard or whatever... (this is what happened to me and many others)
[Nexus 7 Q&A, Help & Troubleshooting] dkhai1234:
Hi,

I was just finished replacing my screen for my nexus 7. However, when I try to power it up, it is not powering up or should I say the screen won't come up, I checked everything. I know that the battery is not dead because the machine alarm went on this morning. If anyone could help, I would appreciate it. Also, as I have been researching, I was thinking that the ribbon cable is at broken so I tried order a new one from ebay waiting for to be delivered and hope this will work.

If anyone could help, please answer.

Thanks in advance
[Nexus 7 Q&A, Help & Troubleshooting] 100012148:
I just get unknown USB device, device descriptor failed, like as if the PC sees nothing.
[Nexus 7 Q&A, Help & Troubleshooting] kierancos96:
I have the same issue. I had MIUI V6 installed on my Nexus 7 (2012). I haven't been using it as much lately, I was using it one day and the battery ran out. I put it on the bed and didn't try to use it for a week or so. When i tried to turn it on, there was no power, I plugged it in, left it charging, but when i came back there was no power, or even a charging icon. I played around with it plugged into the laptop and eventually got it into the bootloader. From there I just pressed start and it wouldn't boot. I haven't managed to get it into bootloader since that. It shows up as 'unknown usb' when plugged in to laptop. Does anyone have any idea to what i can do to fix it/get into bootloader? Thanks
[Nexus 7 Q&A, Help & Troubleshooting] erica_renee:
I have the same issue as the last few above. I was keeping my nexus in my Purse when going to Doctor appts and so on.( I have a note 10.1 tablet that never leaves my hands) .But forgot to charge it for a week. After 3 days trying to revive it .I GIVE up..Good news is i have a square trade warranty. I filed a claim last night . They sent me a Fed-Ex shipping label this morning so im sending it to them for repair. Glad i spent the 34.00

my nexus is the last model of the 2012 32 gb Its been only Lightly used since i got the note a month later. and had a acer 10 inch tablet at the time as well.

---------- Post added at 03:49 PM ---------- Previous post was at 03:45 PM ----------

if you use usbdview app on your windows box and remove the usb drives . it will Show up as apx mode device . But its random took me a few times . and then same as the post below yours. You still cant get anywhere. I Really feel its in coma. (sleep of death) of some kind.

its a shame .

Im going to miss it while its away being fixed
[Nexus 7 Q&A, Help & Troubleshooting] 100012148:
N7 will not power up

Hi,

I have tried everything you say here, my battery voltage is good

When i plug it into the PC via a USB I get apx no driver found

Joe
[Nexus 7 Q&A, Help & Troubleshooting] nickargas:
i'm having the same issue... i've just measured my battery and it has 0.93 volts still inside and i can't turn it on... can u make a small walkthrough with photos or a small video so i can try that aswell? i'm also thinking of trying to measure the voltage output on the battery socket placed on the mobo, when the n7 is plugged on the wall charger and see if i get some voltage there too...

can u help me out? i just got this n7 as a present from a friend and i'm kinda bummed it doesn't work...
[Nexus 7 Q&A, Help & Troubleshooting] conor.cassidy:
response to query

To: nickargas;53450095]

Hi

you will not need instructions for opening the device...(xda has this covered elsewhere).

I have posted 3 photos of the rig I used. ( rig is an exaggeration). The other end of the cable is connected to the factory charger.

The meter reading shown is for a full battery. I have not managed to get an accurate diagram of the pin connection power readings.

The cable is an old nokia usb to phone. (puts the modern cables to shame. (inferior copper etc))

I have noticed that when using the factory charger the battery level will only go to 98%, then i have switched to a 400mA charger and this would get the battery to "charged" (100%).

I will be attempting to bluetooth a new rom (CM 11 M3) to the device and then install it, this is the last resort before I start spending actual cash.

I will not install the gapps package until I have sorted the charging issue.

I have opened a separate thread on the Nexus 7 Q&A, Help & Troubleshooting page and I will update my attempts there for any interested parties.
[Nexus 7 Q&A, Help & Troubleshooting] nickargas:
thanks a mil man... will try that too but i measured mine and it does have some juice in it... measured the mobo battery socket and pogos while i had it on the charger and it didn't showed any voltage...
[Nexus 7 Q&A, Help & Troubleshooting] capquazar:
Glowing screen and refurbished twice

Hey there,

just wanted to tell my story as well.

In short:

My Nexus is working again --> I simply had to turn the glowing screen off somehow (POWER+UP at the same time for 15+ seconds) and let it sit for 10 hours - then it turned on and had to load for another 10 hours.

The full story:

My problem was a non functioning Nexus 7 (2012) suddenly after extensive use - I imagine the battery just went dead, as for many. I immediately called Google (Germany) and they send me a refurbished one without any problems.

Which I then witnessed was the glowing screen at my first refurbished Nexus, when the the plug is connected - and nothing helped, whatever button combination for how many minutes I pressed, as well as having it connected for nights to different USB connectors (two original ones, one from my xperia z1, iPhone as well). Just no battery indicator - nothing, only glowing when connected.

So I called them again and said, sorry broken, now what? So they simply said: replace again. Me: OK.

3 days later, again the same "broken" refurbished problem - again the glowing bug. So I investigated and found different sites and solutions. And which finally worked for me is the following:

I followed the procedure as Google explains on their support site "My Nexus device won't charge or turn on"

but with one difference:

Instead of simply plugging the device in for 10 hours with the glowing screen, I listened to another fellow form the community, who tried to turn the screen of with a magnet, which didn't work for me, but the button combination of POWER+UP seemed to disable the screen (while connected) - and I let it sit there for the 10 hours (on my iPhone USB connector - which I think is irrelevant).

After 10 hours, it DID TURN ON - whaoh - but only for a minute and then died due to empty battery - but finally loaded with the usual battery symbol - so I let it sit there for another 10 hours - and now, after days research and 20 hours being hooked up my 2nd refurbished Nexus is working!

And in retrospective, probably my first Nexus could've had the same problem.

Hope I could help

Cheers

quazar
[Nexus 7 Q&A, Help & Troubleshooting] Gloftking:
I have a similar problem

hello everyone I am currently having a very similar issue you are having but for a very different reason

one day I tried to play the android game NOVA 3 on my Nexus 7 on the highest graphical setting so I went and researched how to do this. I was pointed towards some kind of app called 'ChainFire 3D', Once I pressed the install button inside this app the Nexus 7 switched off and the next time I tried to turn it on I got the X logo of death (boot loop). I then tried to enter recovery and I got the annoying 'no command' error. I cant seem to remember how I rooted this thing but I do have access to the fastboot stuff (inside cmd) and I can't figure out how to get the adb working.

if there is anyone who has any idea how to go about fixing such an issue without wiping everything on my nexus could they please get back to me ASAP. http://xdaforums.com/imag...rs-crossed.gif
[Nexus 7 Q&A, Help & Troubleshooting] ravia:
Nexus 7

I had recently changed the touch screen and lcd togather. after that iam not able to start Nexus 7. but when i am connecting the same to compute, it is visible in device manager as portable device. can any one help me what to do.
[Nexus 7 Q&A, Help & Troubleshooting] Bozz5384:
Unfortunately, my wife's Nexus 7 appears to be dead (even though she had connected it to a charger before it was completely dead) and won't come back on. I've charged it more than 20 hours, with no signs of life. After finding this thread, we even removed the back and unplugged the battery (connector was tight). Left it out for 5 mins or more and plugged it in, put the back on, and still... nothing.

I've tried USB connection to my computer (it makes connection noises on my computer but nothing). Tried powering on with various button combinations, etc.

Anything I am missing? I've read the OP several times and haven't found anything I haven't done.

Frustrated, went from a 100% good working device to nothing.
[Nexus 7 Q&A, Help & Troubleshooting] conor.cassidy:
advice
[Nexus 7 Q&A, Help & Troubleshooting] vibsco:
Battery drain problem

Sorry if I post this in the wrong place as I am using the help from this forum for the very first time. I have a doubt regarding the battery drain in my nexus these days...After charging it completely the first 10%(100-90) lasts through almost 8 hours and then the next 30%(90-60 ) just takes takes max 2.5 hrs to drain. After that the last 40 % works normally I guess and in total I get 1 day battery life.Why is this happening?? Is it normal.? And i use the GSam battery monitor to see which app is causing the most drain and its always showing android system with max 5.1% followed by Kernel(Android) with 2.8%and then system(ndroid.systemui) with 2.3%. All other apps just showing max upto 0.8%.Excluding that it shows display is using the most of it(39.9%) while I rarely open it. Why is this happening?? And for the info I bought my Nexus 7 2012 on January 2014 only and is running android 4.4.4.
[Nexus 7 Q&A, Help & Troubleshooting] eddytheyeti2:
Same issue, no fixes working

Hey everyone, I have had my Nexus 7 for a while now, and I noticed this issue before. In the past all of these workarounds fixed my problem, however this time no button combination, moving chargers, moving plugs, etc. is working. I cannot get it to turn on at all. I need it to turn on currently. It was way outside of warranty, and running Pac-rom. I do not remember which Recovery, but pretty sure TWRP. Any help is much appreciated.

UPDATE: plugging into my computer, I see APX under other devices. However, windows cannot find any drivers for it. Holding the power button did indeed make the devices refresh and showed the APX again. Probably useful information for anyone looking to help me.
[Nexus 7 Q&A, Help & Troubleshooting] ravia:
nexus 7 not switching on

I had changed my screen of nexus 7. But after that my nexus 7 is not turning on. I have tried every thing from charging, replacing battery. But there is no improvement .

I have observed that while connecting to my PC , I am able to see the device as potable media device. But when clicking the same it is opening a new page. Which is empty.

What I have to do?can anyone suggest something.

Ravi
[Nexus 7 Q&A, Help & Troubleshooting] spark001uk:
This is a bit of a strange one, not quite like anything explained here.

Ok, so the winter's here and I've dug mine out for another look. It updated straight away to 4.4.3, then 4.4.4. So I've run a few charge cycles and it's still largely similar - it will only reach about 16 - 18% according to the os, but the same as I checked before, with a meter the battery itself is sat at 4.2V (fully charged), but the os thinks it's 3.7ish V. (according to a number of battery apps)

The thing shuts down nearer to 0% now, at which time it reports around 3.5V, but measure it with a meter and it's actually at just on 4V. So the battery is just fine, and charging is shutting off correctly at 4.2V, but the os thinks its about half a volt lower.

I'm guessing that because the os is reporting an incorrect voltage then no amount of calibration apps will be able to fix it? Any ideas at all?

It can't be the battery surely, it holds its charge fine, even after a number of weeks. I've tried factory reset from both the os and from recovery, battery pull, everything.
[Nexus 7 Q&A, Help & Troubleshooting] fwayfarer:
you can try powering it on to recovery when the battery is 'dead' according to android, then let recovery run until the device will no longer power on at all. then fully charge to 100% before using the device again.
[Nexus 7 Q&A, Help & Troubleshooting] stevey500:
My solution for ultra-dead nexus 7 2012's

Every nexus 7 2012 model I have ever had in my hands that does NOTHING when plugging into the charger, in a quiet room, if you put your ear up to the back near the processor (lower right corner from the back), you can hear a high pitched slow "tick,... tick" repeatedly. It sounds as though the power management on the motherboard is trying to feed power and repeatedly giving up.

In a dark room, you can see the LCD display is actually flickering, a TINY bit of light from the backlight will slightly blip every few seconds, going right along with the slight tick sound from the rear. So, I figured, how do I reduce the load on the power circuitry on this sucker and give it a chance to fully power up? This thing obviously has a DEAD battery and will not charge because the load on the power circuitry is just tacked out... disconnect the LCD. As soon as I disconnect the LCD on N7 2012's that have this issue, I can then hear a constant high pitch whine ( very faint ) if I put my ear near the processor unit. This tells me that it is powering up and now charging. I'll leave it like that for 10-15 minutes, return and plug the LCD in and find it sitting at the bootloader charging graphic. Power it up, success.

I believe either the batteries or the power management circuitry in these are just slightly programmed/engineered incorrectly and allowing the battery to get just slightly too-low and reporting incorrect voltages; giving the power circuitry too much to do when you attempt to recharge after a deep battery drain.
[Nexus 7 Q&A, Help & Troubleshooting] JiJiTheFox:
Hi All,

I've read through this thread, countless other forums and I'm not sure if this is a power issue or if the Nexus is scrap material.

It was find a week ago, infact I popped it on charge at 40% whilst I went out for the day, came home 6 hours it was off, no power on, no fast boot, no boot or ligth or anything.

(don't get me started on button press combos please, I fell asleep trying to do one the other nigh after holding it over 15 minutes. I've tried this many times in hope)

Battery was connected, PC cannot communicate with it for a hardware ID and info, so I replaced the USB board. Still no change.

If this is the battery, would replacing it bring it to boot, would a dud battery still boot if assisted by USB power?

I've even tried the jump start battery method, and no luck.

I'm not sure if I want to fork over for a new battery if it's in vain.

Any help is appreciated.