| Problem | Likely Cause | Fix |
|---------|--------------|-----|
| fastboot oem unlock fails | No unlock code | Use EDL method with QFIL + patched bootloader |
| Phone stuck in EDL | Corrupted boot | Re-flash stock firmware via QFIL |
| Touch unresponsive after unlock | Wrong boot image | Flash stock recovery & boot from Vivo firmware pack |
| IMEI = 0 | NVRAM wipe | Restore QPST backup or write IMEI with Maui META |
After QFIL completes:
Warning: Unlocking the bootloader will factory-reset the device, may void warranty, and can cause data loss. Proceed only if you accept these risks. unlock bootloader vivo y71 high quality