Need to reset CMOS. No Reset button. No jumper. No battery

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Mugsy

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I have a Win10 tablet where the USB ports were inadvertently disabled in the Bios.

I need to reset the Bios back to its defaults. The tablet has no Reset button. There is no jumper inside, no coin-cell battery, and disconnecting the built-in battery packs didn't work.

Is there another way to clear the CMOS? (note: I can't get back into Windows, and can't run ANY programs of any type. I can get into the Bios, but can't make any changes once I'm there.)
 

10tacle

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WOW you've been a Tom's Hardware member for longer than most here at least with a single account. Anyway, what tablet make and model? Can't help much without that info.
 

10tacle

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So you cannot make any changes in BIOS like a boot drive priority change? That would have been my answer and then try and boot from a USB drive loaded with an ISO Windows 10 burn you did from the license. You can try this instruction set from an Insignia rep from a few years ago on a different model of Windows 10 tablet, but bear in mind it will nuke everything you have on that tablet's drive.

If you would like to go ahead with the factory reset, follow these steps:

-Ensure the tablet is connected to the charger and has at least 45% battery left. If the battery dies during this process the device could be damaged.

-Power off the tablet fully.

-Press and HOLD the Volume + button.

-While still holding the Volume + button, press the Power button until the screen illuminates and shows Insignia. Then release the power button only.

-Continue holding Volume+ until one of two screens appear:
---->A) Screen appears with only an Android mascot in the background. If this happens simply let go of volume + and press it one time. You should then see the screen shown in item 'B'
---->B) List of options in the top left of the tablet screen.

-Use Volume - to select "wipe data / Factory reset" and press the power button to select it.

-Use Volume - to select "Yes -- delete all user data" and press the power button to select it.

-Following the reset, the device should boot up and go through the initial setup process again as when it just came out of the box.
 

Mugsy

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Thx for the reply. This entire mess began attempting to find a way to boot from a USB flash drive, and in the process, I inadvertently disabled the XHCI controller, disabling my USB ports (and anything that needs them like my detachable keyboard. So I am unable to navigate the Bios even once I get in.

Unfortunately, the instructions you provided only apply to an *Android* tablet. Using (basically) the same procedure on a Win10 tablet simply gets you into the AMI bios (Volume Up + Power at startup.)

The Volume rocker acts as Up/Down and the Power button acts as "Enter", but there is no way to move left/right to navigate through the menus to get beyond the first page.

I was (past tense) able to log into & use Windows using the on-screen keyboard, and I found software that claimed to allow you to reset the CMOS from within Windows, but it didn't work. The furthest I got was to clear the RTC (which I believe is just the first 14 bytes of the CMOS.)

I also attempted to Flash the Bios from Windows but that too failed. Windows (especially Win10) goes to great lengths to prevent nearly all low-level access to the system through it. UEFI has such limits as well, making it doubly hard to do what I needed.

After a bit of research online, I found a number of links reporting that it is possible to reset the Bios from Linux, so I attempted to install a dual-boot of Linux, but this too is almost impossible without a USB boot drive.

I thought I finally found the answer with "WubiUefi", a new UEFI version of "Wubi" that is supposed to allow you to install a Dual Boot of Linux along-side Windows on the same computer.

But it didn't work. It installed a Boot Menu with no touch-screen support. The "menu" is a horizontal row of three icons. The first OS where the Linux iso should be is instead an empty box (which is auto-selected after 10 seconds reporting "iso not found".) Windows is the second icon on the menu. But since I can't move left/right (only up/down), I can't get to it. :sarcastic:

So now I have no way of running anything at all.

As noted in my original question, "The tablet has no Reset button. There is no jumper inside, no coin-cell battery, and disconnecting the built-in battery packs didn't work."

I found one post online describing a way to reset the Bios by shorting a pin on the Winbond FlashRAM chip but that too did not work. The chip is in a "locked" state.

There must be a way to clear the CMOS that I'm missing.
 

fagetti

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What chip is it (winbond bios chip)? There is model number if you look closely with magnifying glass or scope. If cant see clearly use isoprophyl alcohol with qtip and gently rub it with alcohol and then immidiattely check wwith magnifying glass you should see model number.

What pin you shorted ? Did you do it when battery was connected or not? Did you try to power on while doing it?
 
Aug 23, 2018
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most winbond chip has reset pin, so you can use small cable that connect this pin to ground, press power button and immediately do this, you will see that everything will be clear include your nandflash.. so when you do reset pin to ground, the flash chip working at the beginning from its software and it will create new efi partition on your flash drive.

I had same semptom on my Casper T8W windows tablet, I wrongly disabled XHCI USB and tablet lost OTG ability, I did this method and worked for me.

My flash chip was Winbond 25Q64F 1.8V SPI and it’s 7th pin had /RESET property. (I found this on the data sheet)

I saw which you share photo that I tought it is wrong pin, because 2th is not reset pin on 25Q64F flash chip. you have to use 7th pin.

Good Luck,
Bulent
 
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