You must enable "Diagnostic Mode" on your phone. This is usually done via a secret code (e.g., *#*#717717#*#* ) or through ADB commands.
: Saving critical device-specific information like IMEI, baseband versions, and RF calibrations. nvitems reader writer v10 download link
Are you trying to fix a or just looking to back up your IMEI for safety? How to backup & write NV to Mediatek using Miracle Box You must enable "Diagnostic Mode" on your phone
: Ensure you are using a high-quality USB cable and have enabled "USB Debugging" or the specific hardware diagnostic mode on your phone. nvitems reader writer v10 download link
Always click Read first to back up your original .txt or .qcn file before attempting any writes.