Xiaomi Redmi Note 9 is one of the most popular smartphones in the budget segment, but its capabilities are not limited to standard MIUI functions. Developer mode provides access to hidden settings that allow you to fine-tune performance, debug applications or even unlock the bootloader to install custom firmware. However, not all users know how to properly activate this mode without risk to the system.
In this article, we will not only discuss the basic way to turn on the developer mode, but also the nuances of working with USB debugging, OEM unlocking and hidden MIUI 12/13/14 options. Special attention will be paid to security - why not turn on all the parameters in a row and how to avoid accidental data loss. If you plan root access or firmware via fastboot, this knowledge will help avoid typical errors.
What is a developer mode and why you need it on Redmi Note 9
Developer Mode is a hidden Android settings section designed to test and debug apps. On the Redmi Note 9 (the Mediatek Helio G85 and Snapdragon 720G models), it allows you to:
- 🔧 Enable debugging on USB work-in ADB and Fastboot;
- 📱 Unlock. OEM Unlock (necessary for custom firmware installation);
- ⚡ Optimize performance through animation and background settings;
- 🔒 Change access rights for applications (e.g., allow background activity).
Without this mode, it is impossible to perform many operations, for example:
- 📲 Install TWRP Recovery;
- 🔄 Scroll Global ROM on the Chinese version of the smartphone;
- 🛠️ Use tools like XiaomiTool or MiFlash.
However, on Redmi Note 9 models with MIUI 14 and later, some options can be blocked by the manufacturer – for example, unlocking the bootloader requires binding a Mi Account and waiting 7-15 days.
⚠️ Warning: Activating developer mode disables automatic password locking after rebooting. PIN, Reset it in the settings. → Screen locking.
Step-by-step: how to turn on the developer mode on Redmi Note 9
The activation process is the same for all Redmi Note 9 (4G/5G/Pro/Pro Max) modifications, but may vary slightly depending on the MIUI version.
- Open Settings (the gear icon on the main screen).
- Scroll down and select About Phone.
- Find the MIUI version string and tap it 7 times in a row.
- After 3-4 taps, a notification will appear: “You are almost there!”. Continue until you see the message “You are a developer!”.
If you have MIUI 13/14, you may need to enter a Mi Account password or a graphical key, a security measure to prevent accidental activation.
I've been hitting MIUI Version 7 times |
You have received a notice saying, “You have become a developer!"|
In the menu "Settings" appeared the section "For developers" |
The system did not request additional authentication.-->
After activation, a new option will appear in the main Settings menu — Additional → For Developers (in some versions, just For Developers). If it is not, use the Settings search (the magnifying glass icon at the top of the screen).
⚠️ Note: Redmi Note 9 Pro with MIUI 12.5 Enhanced section may be called "Advanced settings" → Developer settings. It's not a mistake, it's just a localization feature.
Where to find and how to enable debugging by USB
USB debugging is a key feature for connecting a smartphone to a computer via ADB (Android Debug Bridge).
- 🖥️ Install TWRP Or OrangeFox Recovery;
- 📱 Sending custom software through fastboot;
- 🔧 Use tools like Scrcpy to control your phone from a PC.
To enable debugging:
- Go to Settings. → For developers.
- Scroll down to the debugging block.
- Activate the "Debugging by USB" switch.
- In the window that appears, click "Allow".
When you first connect to a computer on the screen of the smartphone will be a request for confirmation RSA-Never click "Always Allow" on public or other PCs, which could compromise your data.
💡
If USB debugging doesn't work, check if Charge Only is active in the notification curtain, and make sure you use the original USB Type-C cable, which may not support data transfer.
Unlocking OEM: What it is and how to enable
OEM Unlock is a must-have step for custom firmware, root rights, or alternative recaps. On the Redmi Note 9, this option is hidden deeper than USB debugging, and its activation has nuances:
- 🔓 Nana MIUI 12 and older unlock requires a Mi Account;
- ⏳ After the option is turned on, you need to wait 7-15 days (depending on the model);
- 📵 Unlocking will reset all data on the phone (full wipe).
To enable OEM Unlock:
- Go to Settings. → For developers.
- Find the option “OEM Unlock” (may be called “Factory Unlock”).
- Activate the switch and confirm the action.
If the option is inactive (grey), it means:
- 🔒 Phone is tied to Mi Account, but it hasn’t been 7 days since the first link;
- 📱 The device was purchased in China (requires unlocking through Mi Unlock Tool);
- 🔄 The phone has an unofficial firmware (for example, Pixel Experience).
What happens if you turn on OEM Unlock without waiting?
| Redmi Note 9 model | Waiting period for unlocking | Is a Mi Account required? |
|---|---|---|
| Redmi Note 9 (Helio G85) | 7 days | Yes. |
| Redmi Note 9 Pro (Snapdragon 720G) | 15 days | Yes. |
| Redmi Note 9 Pro Max | 15 days | Yes. |
| Redmi Note 9 5G | 7 days | No (only for Chinese ROMs) |
Hidden MIUI features for developers: what can be configured
In addition to debugging and unlocking, there are more than 50 options hidden in the developer menu.
1. Accelerating animation
By default, MIUI uses smooth transition animations that can slow down on weak devices to speed up:
- 🎯 The scale of window animation → set up 0.5x;
- 🎯 Scale of transition animation → 0.5x;
- 🎯 Duration of animation → shut down completely.
Background processes
Restricting background processes saves battery power, but can close the desired applications.
- 🔋 Process limit → Standard Limit (Do not put without background processes!);
- 🔄 Don't keep up → Turn it off if you are using multitasking.
3. Display settings
For AMOLED-Additional screen options (on the Redmi Note 9 Pro) are available:
- 🌗 Simulation of color space → sRGB for more natural colors;
- 🔦 Minimum brightness → Reduce to 10% for comfortable reading at night.
Debugging by USB|
Unlock OEM|
Setup of animation |
Limitation of background processes |
Other-->
⚠️ Attention: Change of the parameter "Forced" GPU-Acceleration can lead to graphic artifacts in games and applications.On the Redmi Note 9 with Mali-G52 MC2 It's particularly critical.
Security: What developer settings are best not to touch
Not all of the options on the developer menu are harmless.
- 🚨 Disrupt the sensors (for example, turning off the "Absolute Volume Level" will break the sound adjustment);
- 🔋 Speed up battery discharge (constant activity) ADB background);
- 📵 Disable communication modules (change of Modem settings).
List of dangerous options that are not recommended to change without a clear understanding:
| Parameter | Risk |
|---|---|
| Turn off the absolute volume level | Breakdown of speakers when connecting headphones |
| Selecting a USB configuration (MTP/PTP mode) | Loss of communication with PC when choosing the wrong one |
| Enable 4x MSAA | GPU and lag overheating in games |
| Disable package authentication | Vulnerability to malware |
If you accidentally change a critical setting, reset the developer settings:
- Go to Settings. → For developers.
- Click on the three dots in the upper right corner → "Reset settings".
💡
Before experimenting with the developer settings, back up your data through Settings → System → Backup. This will save your files if you crash.
Frequent problems and their solutions
Even after activating the developer mode correctly, Redmi Note 9 users face typical errors.
1. USB debugging is not enabled
Reason: The phone is active mode "Only Charge" or uses a non-original cable.
Decision:
- 🔌 Connect the phone to the back port USB 3.0 on PC;
- 🔄 Reboot your smartphone and try again;
- 🖥️ Install Mi drivers PC Suite from the official website.
2. no option "OEM Unlock"
Reason: The phone is purchased in China (global firmware required) or the Mi Account is not tied.
Decision:
- 🌍 Please Global. ROM via MiFlash;
- 🔑 Get a Mi Account and wait 7 days;
- 📱 Check if the option is hidden in "Additional settings".
3: The computer does not see the phone in Fastboot mode
Reason: Google USB Driver is not installed or the USB port is faulty.
Decision:
- Download Platform Tools from the Android website;
- Open the Command Prompt in the folder with the platform-tools;
- Enter the command: fastboot devices If the list is empty, drivers are not installed.
💡
If fastboot doesn’t recognize the device, try connecting the phone to a different USB port or using a cable from the original Xiaomi charger.