WARNING: Never Change Radio Band

[TomKay]

Perhaps this warning will save some users a lot of painful hours.

I just spend hours on end to get my phone back to normal because I had accidentally changed the radio band to "USA band" and there is no easy way to revert that.

Now one could argue I should not have accessed the testing menu in the first place, but the phone was getting a bit warm at the back and I wanted to check the temperature. I had forgotten where to look exactly so I looked around a bit and once I saw "radio band" I was curious which options would appear.

After selecting "radio band" only one choice popped up "USA band". Now had I not been still a bit stressed from a phone call and been a bit too tired, I might have figured out that I should have pressed anywhere outside the button, but, PLEASE, if there is only one option, how can it be a wrong one way street?

I had to backup the phone, factory reset it, restore the data and recreate all my settings and app icon arrangements. I couldn't choose the firmware I had been happy with but had to jump to 157 (with unknown consequences). I had issues with some applications which updated to newer versions without my approval so some saved game states won't load back anymore. Luckily, I could revert to an older version of Chrome which does not ignore bookmarks placed on the homescreen (why do bugs like that not get fixed? But I digress). I had to find a workaround for my phone being unable to pair with my PC anymore and luckily I found an answer on this forum.

Fortunately, I anticipated that my app icons won't reappear at their previous positions despite the fact that I tried the phone back up and a PC companion backup, and had taken pictures of my home screens before the factory reset.

I literally spent six hours just because my finger was a split second quicker than my brain when I was faced with a "one option"-choice while searching for the temperature reading.

I appreciate that a testing or a service menu must be approached with caution, but even experienced technicians make mistakes from time to time. AFAIC, there should be no way (I'm sparing you the expletives here) to essentially render your phone useless with one touch of a button 

1. without an explicit alternative being offered (implying the one choice must be OK), and
2. without being asked for confirmation (for such a significant change), and
3. without an option to go back and reconfigure the correct band (why make it a one way street?).

It leaves me puzzled how anyone could set up a combination of all these three factors, be it in a service menu or not.

[johnlarn18]

same problem here. i accidentally press the USA radioband.. and now i dont have signal most of the time. please somebody help

[Sydneyferguson]

What about Android Fastboot Reset Tool is it related to this?

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@SiddharthJose wrote:

You've two ways to save yourself from a complete data wipe and a fresh rom install. Works without ROOT access.

Option One (universal except for most samsung phones)

1. Enable "USB debugging"

2. Download and install adb tool to your PC from "https://androidmtk.com/download-minimal-adb-and-fastboot-tool"

3. Connect your phone to PC with a data cable.
(your phone will be detected by PC at this step. If not download manifacturer drivers)

4. Allow USB debugging

5. Execute the desktop shortcut and type "adb devices" if it returns a number youre good to go.

Input the following

adb reboot bootloader  (If you are already on the bootloader skip this)
fastboot erase modemst1
fastboot erase modemst2

fastboot erase cache (optional but recommended)
fastboot reboot

---------------------------------------------------------

This should work.But In case youre still stuck....

Option Two (universal except for most samsung phones)

1. Download your phone's stock rom. Links: http://www.androidrootguide.com/download-stock-rom-smartphones if you cant find it there..google will come to your rescue just ask for help

2. Extract the rom file and identify the modem file namely NON-HLOS.bin (in the unlikely event of having a different filename, figure out what the .bin files contain using google search and copy and use the file that has the modem band information instead of the mentioned file)

3. Copy this file to the folder where the adb toolkit is installed (Default :C:\Program Files (x86)\Minimal ADB and Fastboot)

4. Connect your phone to PC with a data cable & Allow USB debugging

5. Execute the desktop shortcut and type "adb devices" if it returns a number youre good to go.

Input the following

adb reboot bootloader  (If you are already on the bootloader skip this)

fastboot flash modem NON-HLOS.bin (or "fastboot flash modem filename.bin")
fastboot erase modemst1
fastboot erase modemst2
fastboot erase cache (optional but recommended)
fastboot reboot

http://www.crunchytricks.com/2018/06/android-fastboot-reset-tool.html

This should have done the job. You're welcome :

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[pakajsinghk062]

Thanku very much this is so helpful for my redmi 4X(santoni).

[CJo5]

I actually was just messing with mine that's how came across this thread..

Just download 

ZERO PERMISSION APP 

from app store.. it gives you info about your whole phone without asking for any permissions.. u will be able to change it there

Mine says

Automatic

United States

Cellular 800

PCS