You have two dangerous options:
If you need to move forward with this process, please let me know: What is the exact of your Qualcomm device? What operating system is running on your computer? What error message or status do you see when dialing *#06# ?
There is no single "best" tool; it depends on your chipset and brand. Here are the industry standards.
Check the box for (since the donor QCN file has a different serial structure). Click Start and wait for the progress bar to reach 100%.
Disclaimer: This article is for educational purposes only. Modifying IMEI numbers is illegal in many jurisdictions. Proceed with caution.
You must have the original IMEI numbers printed on the retail box or device sticker to write them back legally. Step-by-Step Guide to Using a QCN IMEI Repair Tool
Never flash a QCN file meant for a different phone model, or even a different regional variant of the same phone. Doing so can permanently damage the physical RF transceiver chip, causing permanent hardware-level "No Service" faults.
This guide is a common workflow used for many Qualcomm devices. It assumes you have lost your IMEI and have downloaded a backup QCN file or a stock QCN for your phone model. Warning: This is for educational purposes only. Do not attempt this unless you are experienced.
This is where a becomes essential. These tools are designed to fix, restore, or modify the IMEI number by interacting with the device’s radio frequency (RF) calibration data. What is a QCN File?
Qualcomm is the manufacturer of processors in 90% of Android phones (Samsung, Xiaomi, OnePlus, Google Pixel, etc.). These chips use a specific partition called (Qualcomm Calibration Network).