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How to bypass fastboot low battery warning / FAILED (remote: Warning: battery's capacity is very low)

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Bishnu840

Member
Dec 26, 2013
23
2
chittagong
Realme X2
Hello Everyone I'm writting this post to hoping that This would help many people. Because I didn't find any proper solution for this on the internet.

Scenario: Suppose you flashed wrong file or did something wrong and somehow you bricked your device in such a state where your device will only go to fastboot mode stable or unstable fastboot mode ( fastboot restarts itself after few seconds).
Means your boot/recovery all destroyed. Luckily your bootloader is unlocked. So you felt realx thinking that you can flash recovery/boot from fastboot to fix your device. Then you flashed an image through fastboot and saw an warning like " FAILED (remote: Warning: battery's capacity is very low)".
Screenshot (12).png

Thats when the problem begins .
It's because before device got bricked it had very low charge. And without boot or recovery image your device don't know how to charge itself. So weather if your device is in fastboot or edl 9008 don't expect it to charge itself. And by fastboot rule it won't accept any file if it has low battery.
For exactly below 3478mV any file writing is unacceptable.

I found a solution on XDA How to fix the 'Low Battery' fastboot loop . Basically it's a fastboot script which restarts bootloader in a continues loop to charge it in the mean-time of reboot to fastboot.
Code:
@echo off
:start
fastboot getvar battery-voltage

fastboot reboot-bootloader

ping /n 6 localhost >nul

goto start

I mean no disrespect to that post, The way it was trying to do it maybe it make some sense but not much.
Because like others I have run this script for several hours for several times and got no result. I was running this script on laptop then i thought maybe laptop is not giving proper output delivery. Then I tried with my desktop back usb port but no good.
Instead for running this script so long that in those thousands reboot my device surely lost some of its lifetime early and it corrupted my internal partition which I've discoverd after fixing my device.

Ok then the next option I had was opening the backshell which I don't want. Tried customer service they denied because of unofficial device. Local shops failed also they tried to open back shell but I didn't let them.
So your'e basically doomed like me because Brands like realme doesn't provide any flash tool/flash tool credentials for free. And remote unbrick is very much costly.

Solution:
After trying many things I found an App on play store Called Bugjaeger Mobile ADB - Develop & Debug via USB OTG.

Screenshot_2021-08-25-20-14-58-40.jpg


Requisitions :
1. NO Root Required
2. App itself
3. Good OTG cable
4 Proper USB cable
5. Nothing else 😂

For stable fastboot user:
First download the app in a device which support OTG connection. plug in otg cable.
Now connect your device to other device via OTG in fastboot mode. Now press on < > This icon and type your command like you do In pc
for example "fastboot flash recovery" after recovery give a space and click on attachment icon in the top right corner then select your file. Then run the command .

Screenshot_2021-08-25-20-17-36-78.jpg

Boom you have successfully ignored fastboot low battery warning. Enjoy.

For unstable fastboot users:
I have calculated that my device was restarting in every 5 secons. could be different for you.
So what I did. Before going to fastboot mode the app show some AD.
so first disable it by adding private DNS like dns.adguard.com or better turn off wifi/mobile data.
Then suppose you want to flash recovery so make copy of command 'fastboot flash recovery" this will save 2 seconds and keep your file in your root directory so it will also save time. After everything set hit flash As soon as possible.
My recovery size was 98 mb and It had only 2 seconds to push it to the device. It said " sending recovery ok- writing failed" so you better use good cable.
Means it was able to successfully sent the file but didn't got image writing status because your device got turned off. But don't worry.
sent the img file was all the things we needed. I tried it 2 times and it works.

If it is unclear please watch the video to how to use this app

Tips:
1. Never do any risky task with low battery .


Conclusion : I'm not responsible if anything goes wrong with your device. I shared it only thinking that this will save many people from hassels.
Thank you.
 
Last edited:
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Reactions: devansh8

mike_san

Senior Member
Feb 6, 2013
201
6
So you need a second device via OTG to fix the unstable bootloader?

My case is that the phone works perfectly, IMEI wifi calls etc, recovery works aswell but fastboot is broken.

Restarts after 2 or 3 seconds while holding the button, If release the phone will just boot normally.

This happened right after trying to lock the bootloader again coming from realmen UI 2.0 beta

Any thoughts?
 

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    Hello Everyone I'm writting this post to hoping that This would help many people. Because I didn't find any proper solution for this on the internet.

    Scenario: Suppose you flashed wrong file or did something wrong and somehow you bricked your device in such a state where your device will only go to fastboot mode stable or unstable fastboot mode ( fastboot restarts itself after few seconds).
    Means your boot/recovery all destroyed. Luckily your bootloader is unlocked. So you felt realx thinking that you can flash recovery/boot from fastboot to fix your device. Then you flashed an image through fastboot and saw an warning like " FAILED (remote: Warning: battery's capacity is very low)".
    Screenshot (12).png

    Thats when the problem begins .
    It's because before device got bricked it had very low charge. And without boot or recovery image your device don't know how to charge itself. So weather if your device is in fastboot or edl 9008 don't expect it to charge itself. And by fastboot rule it won't accept any file if it has low battery.
    For exactly below 3478mV any file writing is unacceptable.

    I found a solution on XDA How to fix the 'Low Battery' fastboot loop . Basically it's a fastboot script which restarts bootloader in a continues loop to charge it in the mean-time of reboot to fastboot.
    Code:
    @echo off
    :start
    fastboot getvar battery-voltage
    
    fastboot reboot-bootloader
    
    ping /n 6 localhost >nul
    
    goto start

    I mean no disrespect to that post, The way it was trying to do it maybe it make some sense but not much.
    Because like others I have run this script for several hours for several times and got no result. I was running this script on laptop then i thought maybe laptop is not giving proper output delivery. Then I tried with my desktop back usb port but no good.
    Instead for running this script so long that in those thousands reboot my device surely lost some of its lifetime early and it corrupted my internal partition which I've discoverd after fixing my device.

    Ok then the next option I had was opening the backshell which I don't want. Tried customer service they denied because of unofficial device. Local shops failed also they tried to open back shell but I didn't let them.
    So your'e basically doomed like me because Brands like realme doesn't provide any flash tool/flash tool credentials for free. And remote unbrick is very much costly.

    Solution:
    After trying many things I found an App on play store Called Bugjaeger Mobile ADB - Develop & Debug via USB OTG.

    Screenshot_2021-08-25-20-14-58-40.jpg


    Requisitions :
    1. NO Root Required
    2. App itself
    3. Good OTG cable
    4 Proper USB cable
    5. Nothing else 😂

    For stable fastboot user:
    First download the app in a device which support OTG connection. plug in otg cable.
    Now connect your device to other device via OTG in fastboot mode. Now press on < > This icon and type your command like you do In pc
    for example "fastboot flash recovery" after recovery give a space and click on attachment icon in the top right corner then select your file. Then run the command .

    Screenshot_2021-08-25-20-17-36-78.jpg

    Boom you have successfully ignored fastboot low battery warning. Enjoy.

    For unstable fastboot users:
    I have calculated that my device was restarting in every 5 secons. could be different for you.
    So what I did. Before going to fastboot mode the app show some AD.
    so first disable it by adding private DNS like dns.adguard.com or better turn off wifi/mobile data.
    Then suppose you want to flash recovery so make copy of command 'fastboot flash recovery" this will save 2 seconds and keep your file in your root directory so it will also save time. After everything set hit flash As soon as possible.
    My recovery size was 98 mb and It had only 2 seconds to push it to the device. It said " sending recovery ok- writing failed" so you better use good cable.
    Means it was able to successfully sent the file but didn't got image writing status because your device got turned off. But don't worry.
    sent the img file was all the things we needed. I tried it 2 times and it works.

    If it is unclear please watch the video to how to use this app

    Tips:
    1. Never do any risky task with low battery .


    Conclusion : I'm not responsible if anything goes wrong with your device. I shared it only thinking that this will save many people from hassels.
    Thank you.