The ZTE Avid 4 (model K81) is a compact, budget-friendly smartphone designed for essential daily use, often associated with US prepaid carriers. It provides a standard Android experience powered by a Qualcomm Snapdragon processor. This guide is for users who need to restore their device to its original factory condition. The provided QFIL firmware is a low-level unbrick package, perfect for fixing a hard-bricked phone that won’t turn on, resolving persistent software errors and bootloops, or bypassing a Google FRP lock.
Important: This is an advanced unbricking procedure. It is not a standard update. This firmware is specifically for the ZTE Avid 4 (K81). Flashing it requires your phone to be in EDL Mode (9008), and the process will erase all data. Proceed with caution.
Quick Device Specs
- Device: ZTE Avid 4 (K81)
- Release year: 2018
- Chipset: Qualcomm Snapdragon 210 (MSM8909)
- Display: 5.0″ TFT Display
- Battery: 2520 mAh
- Original OS: Android 8.1 (Oreo)
Required Downloads
To flash a Qualcomm device in EDL mode, you will need the specific QPST suite and drivers.
| File / Tool | Download Link |
|---|---|
| QPST & QFIL Flash Tool | Download Latest Version |
| Qualcomm QDLoader USB Drivers | Download Drivers |
Unbrick Firmware (QFIL)
| Region / Carrier | Build | Type | Download | Chipset |
|---|---|---|---|---|
| Unspecified (US Carrier) | V1.0.0B05 | QFIL EDL Unbrick ROM | Download | Qualcomm |
How to Flash (QFIL EDL Method)
This method is for restoring a hard-bricked device and will erase all data.
- Install Drivers: Download and extract the Qualcomm QDLoader USB Drivers. Run the installer. You may need to disable Driver Signature Enforcement in Windows for the drivers to install correctly.
- Install & Launch QPST: Install the QPST suite, which includes the QFIL application. Launch QFIL from your Start Menu.
- Enter EDL Mode: This is the most critical step. Power off the device completely. Connect a USB cable to your PC. Now, press and hold both Volume Up and Volume Down buttons on your phone, and while holding them, plug the other end of the USB cable into the phone. The screen will remain black, but your PC should detect the device.
- In QFIL, the text at the top of the window should change from “No Port Available” to “Qualcomm HS-USB QDLoader 9008”. If it does, you are in EDL mode.
- Configure QFIL:
- Ensure “Select Build Type” is set to Flat Build.
- Click “Browse” next to “Programmer Path” and select the prog_emmc_firehose_… file from the extracted firmware folder.
- Click “Load XML” and select the rawprogram_unsparse.xml file, and then the patch0.xml file when prompted.
- Begin Flashing: Click the blue “Download” button. The process will begin, and you will see the progress in the status bar.
- Finish: The process will take several minutes. Once it completes successfully, you will see a “Download Succeeded” message. You can now disconnect your phone and hold the Power button to boot it up. The first boot will take significantly longer than usual.
Device-Specific Troubleshooting for ZTE Avid 4 (K81)
- “No Port Available” / Driver Issues: This is the most common problem. If QFIL doesn’t see the “Qualcomm HS-USB QDLoader 9008” port, your drivers are not installed correctly. You must disable Driver Signature Enforcement in Windows before running the driver installer. Reboot your PC after installation and try again.
- Entering EDL Mode: Ensure the phone is completely powered off. Press and hold both Volume Up and Volume Down buttons simultaneously. While holding them, plug the USB cable into the phone. The screen will stay black, but your PC should make a connection sound, and the port will appear in QFIL.
- QFIL “Sahara” or “Firehose” Error: This error points to a communication failure. Use a high-quality USB cable, connect directly to a USB 2.0 port on your computer’s motherboard (the back ports on a desktop), and ensure no other conflicting mobile drivers are installed.
- Fixing Google FRP Lock: If you are locked out of your phone by Google’s Factory Reset Protection (FRP) after a reset, flashing this official stock ROM using the QFIL “Download” process will completely wipe the device and remove the locked account, allowing you to set it up as new.
FAQs
Q1. What is a QFIL / EDL firmware? QFIL (Qualcomm Flash Image Loader) is a tool used to flash firmware in EDL (Emergency Download) mode. This is a very low-level mode, a step below fastboot, designed to recover Qualcomm devices from a “hard brick” state where they are otherwise unresponsive.
Q2. Will this unlock my phone from its carrier (e.g., MetroPCS)? No. Flashing the stock firmware restores the phone’s original software, but it does not remove the SIM/network lock put in place by the carrier.
Q3. Do I need an unlocked bootloader to use this method? No. EDL mode is a low-level engineering mode that bypasses the bootloader. It can be used to restore a phone regardless of whether its bootloader is locked or unlocked.
