We are providing you with a .rar file to reduce the file size. Please note that you need to convert this file to a .zip format.

Before You Proceed:

This process could erase all data on your device, so you must back up any important files before you start. Losing data while flashing is irreversible, so ensure your backup is complete. Be very careful on these above and follow each step. Because one wrong step can make your device unresponsive or this process may brick your device too.

Prerequisites:

Backup Your Data:

Back up critical files to cloud storage, an external hard drive, or a computer.
Use the built-in backup features or third-party apps to ensure that contacts, messages, call logs, app data, and other vital information are backed up. A full NANDroid backup using TWRP or other custom recovery, if possible.

Charge to Maintain Safe Levels:

Meanwhile, your device must be charged to a minimum of 50% battery to prevent any damage while flashing the ROM.
If possible, please keep the device plugged in.

Download Firmware:

Check the official OnePlus website to get the latest firmware made for the OnePlus 3T.
Note that you should only choose the right firmware to avoid potential incompatibility issues, which will lead to system instability.
Check the checksum of the downloaded file to ensure its integrity.

• If needed, unlock the bootloader:
• This action will wipe everything off your device’s internal storage.
• An official document of OnePlus should provide you with the bootloader unlocking instructions so that your device doesn’t get bricked.

Enable Developer Options:

Enable Developer Mode by going to Settings > About Phone and tapping Build Number seven times.

Step 1:

Enable OEM Unlocking & USB Debugging
Go to Developer Options and enable OEM Unlocking and USB Debugging.

Step 2:

Unlock Bootloader Using Fastboot
Then boot into Fastboot Mode (Volume Up + Power).
USB Cable to connect the OnePlus 3T to the computer.
Launch a Command Prompt or a Terminal and type: fastboot oem unlock

Commit to the prompt on your phone and let the bootloader unlock. The device may automatically reboot itself.

You are going to [ADB and Fastboot] Tools in this guide.

How to Download and Install ADB & Fastboot:

ADB and Fastboot come with the Android SDK in case you haven’t done that, you can download the Android SDK Platform Tools from the Android Developers website.

Ensure Proper Connection:

You can do this by opening Command Prompt or Terminal and entering: adb devices
This should show you the device you are connected with. Otherwise, make sure that the appropriate USB drivers have been installed.

Extract Firmware Files

Unzip the Firmware Package:

Download the firmware files from the OnePlus website, and extract them to a folder on your PC.

Verify Files:

Recovering HTTP files Recovery logs such as logs[ RECOVERY_LOCK_TIMEOUT ] files Log files such as logs[ RECOVERY_LOCK_TIMEOUT ] img, boot. img, system. img, cache. IMG, and user data. Data Extraction After data extraction, four image files are available in the extracted folder.
The actual confirmation screen will show if the file(s) has been/times are-to-be flash right from the content and will also display the actual number of files in that.

Step 1:

• Enter Fastboot Mode on the OnePlus 3T Boot.
• Completely Power off the Device.

Enter Fastboot Mode:

Then press and hold volume up + power at the same time until you see the fastboot screen.

Connect Device to PC:

Connect the OnePlus 3T to the computer using a good-quality USB data cable.
Make sure the cable is connected and not disconnected when you are flashing.

Flashing the Firmware:

Change Directory to the Extracted Firmware Folder:
Launch a Command Prompt or Terminal in the directory you extracted firmware to.
Execute Flashing Commands:

Use the following command to flash each partition:

1. fastboot flash recovery recovery. mg
2. fastboot flash boot boot.img
3. fastboot flash system system. mg
4. fastboot flash cache cache. mg
5. fastboot flash userdata userdata. mg

Make sure file names are exactly matching with those of extracted files.
In case of an error check your file paths and try it again.

Reboot the Device:

After the flashing is done, reboot your device:
fastboot reboot
First Boot Might Take Time:
Wait 2-3 minutes for the phone to boot up and prepare the new firmware.
If the device does not boot and gets stuck on a boot logo, wipe the cache partition or perform a factory reset from recovery mode.

Important Notes:

• The following instructions are generic and for flashing firmware on the OnePlus 3T.
• Steps may differ slightly by firmware version and model device.
• These instructions should be followed at your own risk. Always refer to the official OnePlus documentation, and proceed at your own risk.
• Downloading firmware from untrusted sources can lead to security vulnerabilities.
• You are provisioned on data through October 2023 If your device fails to boot normally after flashing, enter recovery mode and perform a factory reset.
• Note: The steps should be followed cautiously, flashing the firmware incorrectly could brick the device.
• If you intend to flash custom ROMs or firmware updates later on, leave your bootloader unlocked.
• Make sure that Flashing does not get invoked in case your PC does not recognize Fastboot Mode.
• However, if this doesn’t solve the problem, you may need to look into official OnePlus forums or other tech communities focused on OnePlus.

So, if you follow these steps properly, you should be able to flash your OnePlus 3T firmware properly and get it back to its normal state. Do it at your own pace, double-check every step, and do it slowly, you might run into things that will waste your time.