Now I have downloaded Global firmware instead of EU firmware and it was ... sucessful 
Downgrade was also successful.
Starting phone
Connecting to the PC via USB
Starting MsmDownloadTool
Windows11 Pro:
cmd [enter]
adb devices [enter]
adb reboot edl [enter]
phone screen is black
MsmDownloadTool: Connected. Clicking Start, then downgrading successful.
Thanks for you support
(I have bought the phone in the EU, but had to use the global firmware)
Now I have downloaded Global firmware instead of EU firmware and it was ... sucessful
Downgrade was also successful.
Starting phone
Connecting to the PC via USB
Starting MsmDownloadTool
Windows11 Pro:
cmd [enter]
adb devices [enter]
adb reboot edl [enter]
phone screen is black
MsmDownloadTool: Connected. Clicking Start, then downgrading successful.
Thanks for you support
(I have bought the phone in the EU, but had to use the global firmware)
From URL https://community.oneplus.com/thread/1541327 I downloaded Qualcomm_Drivers_Setup.exe from URL https://drive.google.com/file/d/1zKPFtcc2X_Nf70mcvn9TBu60bHl6Q3cP/view
and installed on Windows 11 Pro.
Options:
o WWAN-DHCP is not used to getIPAddress
o ETHERNET-DHCP is used to getIPAddress (choice)
Phone hold Volume Up and Volume Down, plug in USB-cable, release Volume Up and Volume Down
*** Nothing happens ***
According to https://community.oneplus.com/thread/1541327
Method to get into EDL-mode
(Unlock the developer options by tapping the build number 7 times rapidly in About Phone/About Device.)
(Open the Developer options and enable USB debugging.)
Connect phone to PC and type on Windows 11 Pro:
cmd [Enter]
adb devices [enter]
A pop-up appears up on my phone: USB-Debugging -> "always allow"
adb reboot edl [enter)
screen ist black
Device-Manager: COM & LPT: Qualkomm HS-USB QDLoader 9008 (COM3)
MsmDownloadTool Start was still acitvated and MSMDownloadTool automatically worked for 6 seconds, now showing:
COM: COM3
Status of Connection: N/A
Status of Communication: Multi-immage identify by target sw id is disabled
Progress of Download: (green bar)
Time: 6 s
Status of Last Communication: Device not match image (20886)
phone first start only with Vol.UP+Vol.Down+Start -> choose Start -> Start-Button
*** Still Android Version Oxygen OS 11..4.BEB86AA
Does "Device not match image" mean, that the MsmDownloadTool-Version is not matching to the OnePlus Nord N10 5G?
I had downloaded https://onepluscommunityserver.com/list/Unbrick_Tools/OnePlus_Nord_N100/EU_BE83BA/Q/OnePlus_Nord_N100_EU_OxygenOS_10.5.2.zip from https://devices.ubuntu-touch.io/device/billie2/
Now I tried as follows:
Bios: Secure Boot [Disabled]
PC new start
right mouse click: Start menu - „Terminal (Administrator)“.
bcdedit /set testsigning on
PC new start
OnePlus_setup.exe install
OnePlus_USB_Drivers_Setup.exe install
right mouse click: Start menu - „Terminal (Administrator)“.
bcdedit /set testsigning off
PC new start
Start MsmDownloadTool V4.0 as Administrator - Klick Start - Other - Next - Start
Phone hold Volume Up and Volume Down, plug in USB-cable, release Volume Up and Volume Down
*** Nothing happens ***
Bios: Secure Boot [Enabled]
The files I used I had downloaded from my switched on OnePlus Nord N10 5G phone via USB-cable, becaus I could not find USB-Drivers on the OnePlus homepage.
I use Windows 11 Pro.
In the Device Manager the phone is shown as QUSB_BULK_xxx:xxxx_SN:xxxxxxxx when it is on.
I plugged in the phone to windows 11 pro (phone was on) and Explorer showed the following files
CD-Drive (D:) OnePlus Drivers\OnePlus_USB_Drivers_Setup.exe
CD-Drive (D:) OnePlus Drivers\OnePlus_setup.exe
CD-Drive (D:) OnePlus Drivers\adb_config_Linux_OSX.sh
CD-Drive (D:) OnePlus Drivers\AndroidFileTransfer.dmg
CD-Drive (D:) OnePlus Drivers\autorun.inf
I copied the files to the PC, started Windows 11 Pro in Safe mode and executed booth exe-files.
After that I started Windows again in normal mode.
In the Device Manager the phone is still QUSB_BULK_xxx:xxxx_SN:xxxxxxxx when it is on and plugged in.
Startin in EDL Mode still doesn't work.
Sorry, that it took some days to answer.
In the Device Manager are no COM ports listed.
Only USB:
USB-Controller
-Intel(R) USB 3.10 eXtensible_hostcontroller-1.10 (Microsoft)
-USB-Root-Hub (USB 3.0)
-USB-Verbundgerät
USB-Geräte
-Camera DFU Device
The column under COM is empty. Whether the device is in EDL mode or not, I don't know.
Re: How to Downgrade Nord N10 T-Mobile?
Hello,
I have exactly done, what MrT10001 wrote, to downgrade my OnePlus Nord N10 5g from Oxygen OS 11.0.4 to Oxygen OS 10.5.7, but I guess, the phone is not being found by the MsmDownloadTool:
But now, the phone is not shown on the MSM Download list, nor any COM port is listed.
Therefore klicking start in the MSM Download tool doesn't help.
Is it possible, that the phone has a sim-lock?
Is it possible, that Windows 11 doesn't work?