[Android General] Viva La Android R.I.P.:
QLink Serrano 3

Model No. HPP-L55B

By Hot Pepper Mobile

View attachment 5841863

Bootloader Unlocking

And Rooting Guide ​

OVERVIEW:

This guide provides step-by-step instructions for unlocking the bootloader and achieving root access on the QLink Serrano 3. Please note that this guide is specifically for the QLink variant of the Serrano 3 (HPP-H55L), as I have not verified the applicability of this guide on other carrier variants of this smartphone. To simplify the rooting procedure, and to cater this guide to new and inexperienced members, I have provided a boot image pre-patched for Magisk systemless root support below, in the downloads section.

IMPORTANT NOTE: The pre-patched boot image in the downloads section below corresponds with firmware build HPP-L55B-J-9.0.0. If your Serrano is running a different build, flashing the pre-patched boot image provided may or may not result in compatibility issues. In short, the best rule of thumb when achieving systemless root is to always patch an image that matches the firmware build installed on your device, otherwise you may encounter issues such as broken WiFi, broken Bluetooth, or your device may not boot at all. Should any members encounter issues of this sort, you may flash your device with the HPP-L55B-J-9.0.0 firmware by following my firmware restoration guide for the Serrano here: QLink Serrano 3 Firmware Restoration Guide

UNSUPPORTED MODELS:

Some members have reported fastboot yielding Error 0x1000 (FAILED) upon entering the bootloader unlock command. This error is indicative of restrictions imposed by the device manufacturer to prevent the bootloader from being unlocked via the fastboot command line method. The exact reason is not known as to why sone QLink Serrano 3 devices are supported for standard bootloader unlocking while other models are not. This is most likely based on the date of manufacture of certain Serrano 3 devices. In any event, if you have a Serrano 3 unsupported for bootloader unlocking via fastboot, your other option is to exploit the bootloader into an unlocked state by way of the MTK Client software utility for Windows. I have provided a link in the downloads section below for a simplified guide on setting up and unlocking your bootloader with MTK Client. Credit for this guide goes to XDA Member @Sidharth09.

PREREQUISITES:

You will need a Windows PC or laptop with the ADB & fastboot tools installed. I have provided a link below for the latest Minimal ADB & Fastboot tools. You will need the factory supplied, or a quality equivalent micro USB to USB-A data syncing/charging cable. And, you will need your QLink Serrano 3 smartphone. I again emphasize that this guide has only been tested on the QLink variant of the Serrano (HPP-L55B).

DISCLAIMER:

The tasks outlined in this guide encompass inherent risks to the integrity and operability of your smartphone. Moreover, unlocking the bootloader/rooting the device will void any active manufacturer's warranty you may have on your Serrano. By proceeding further, you are assuming full responsibility for the state and health of your smartphone. As such, you are hereby absolving me of any responsibility or civil liability in the unfortunate event things go badly. This guide has been fully and thoroughly tested. Follow the instructions carefully, employ some patience, and pay attention to detail and I'm confident things will go smoothly. It should also be noted that the tasks outlined herein can be carried out using a Mac or Linux computer as well. This particular guide, however, will focus solely on a Windows -based setup.

I.. INSTALLING ADB & FASTBOOT

Because both tasks outlined in this guide require ADB/Fastboot communication between your phone and PC/laptop, this first section will focus on proper installation of the ADB & Fastboot utilities on your Windows computer. If you already have a working ADB/Fastboot environment, skip down to the next section on unlocking the bootloader. Otherwise, follow these steps:​

Download the Minimal ADB & Fastboot tools installer from the link below. Right click the .exe file and opt to run it as an administrator. Follow the on-screen prompts and complete the installation;​

Open the Windows File Explorer, go to This PC and open your C: drive directory. Open Program Files x86 and locate the Minimal ADB & Fastboot folder. Copy the folder and then paste it on your desktop (this step merely configures the ADB & Fastboot directory to a more convenient location from which to work);​

Open the Minimal ADB & Fastboot folder and double click the file named cmd-here. A command prompt will open. Next, connect your Serrano to your Windows computer using a suitable micro USB to USB-A data syncing cable. Ensure that USB Debugging is enabled in your Developer Options menu.​

In the command window you opened in the previous step, execute this command:

adb devices

Watch your device display for a USB Debugging authorization prompt. Grant the request. If properly connected, the command window will output an alphanumeric string consistent with your device serial number;​

If the command window does not display your serial number, or if you get a WAITING notification, your smartphone isn't communicating properly with your PC or laptop. Try another data syncing cable,; change USB ports; and/or reinstall the Minimal ADB & Fastboot tools on your computer;​

Once you have established proper device communication, we will now test fastboot mode communication. Execute this command:

adb reboot bootloader

Your device should now boot into fastboot mode, which will be illustrated by a darkly backlit display with the words => FASTBOOT mode.... displayed in a white font at the bottom-left of the screen;​

Next, execute this command:

fastboot devices

Similar to before, if properly connected, the command window will display your device S/N. If you don't see your S/N, or if the command window says WAITING, you are not properly connected. Again, try changing USB ports, try another data syncing cable, and/or reinstall the Minimal ADb & Fastboot tools on your computer.​

II. UNLOCKING THE BOOTLOADER

WARNING: Unlocking the bootloader triggers a native Android security mechanism that forces the device into a factory data reset. This will erase all saved userdata on your phone. Before proceeding further, make a backup of all saved userdata you wish to keep.​

Open device Settings>System>Developer Options, and enable the OEM Unlock option;​

Boot into fastboot mode by executing:

adb reboot bootloader

Once in fastboot mode, it's time to initiate bootloader unlocking. Execute this command:

fastboot flashing unlock

Your smartphone display will now prompt you to tap Volume + to proceed with unlocking, or Volume - to cancel;​

After pressing Volume +, the unlock sequence will finish in just a few seconds. Now reboot to complete the process: Execute:

fastboot reboot

As mentioned previously, your phone will now initiate a mandatory factory data reset, after which your device will boot into the initial setup phase of the Android OS. Your bootloader is now officially unlocked.​

III. ROOTING THE SMARTPHONE

Now that the bootloader is unlocked, attaining root access is very straightforward.​

Download the patched boot image and vbmeta image files from the links below and save the files in your Minimal ADB & Fastboot folder;​

Double click the cmd-here.exe file to open a command window. Execute this command to flash the patched boot image:

fastboot flash boot patched_boot.img

Now we will disable dm-verity by executing this command:

fastboot --disable-verity --disable-verification flash vbmeta vbmeta.img

Now, execute this command to reboot your phone:

fastboot reboot

Upon reboot into the Android OS, locate the Magisk app or its stub placeholder in your app drawer. Open Magisk, grant any requested permissions, and follow any prompts to finish setting up the root environment. Magisk may initiate a reboot to complete root setup. If the Magisk app or its stub placeholder is not in your app drawer, download the Magisk v25.2 APK from the link below and install it on your phone. That's it. You are rooted with the Magisk v25.2 systemless root solution.​

DOWNLOADS:

• Minimal ADB & Fastboot v1.4.3

• Patched boot.img

• vbmeta.img

• Official Magisk Releases (GitHub)​