Q1. The Face Unlock on my Cubot J8 is very unreliable. Can this be fixed?

Yes, this is the most common complaint for this model. Flashing the latest firmware (V08) is highly recommended, as it often includes improvements to the face recognition algorithms. A clean installation will also fix any software glitches causing the feature to fail.

Q2. My phone is extremely slow, even though it's running Android Go. Will flashing help?

Yes. A clean flash will restore the phone to its original factory performance by removing all software clutter and junk files. However, the MT6580 is an older chipset, so it's important to manage performance expectations and stick to lightweight "Go" apps.

Q3. My phone's battery doesn't last a full day. What's the problem?

Poor battery life can be caused by software bugs or rogue apps. Flashing the latest stock ROM ensures you have the most optimized power management settings from the manufacturer. After flashing, monitor your app usage to identify any specific apps that are draining the battery.

Cubot J8 Stock ROM (Firmware) | Fix Face Unlock & Lag

The Cubot J8 is an ultra-budget smartphone from 2020 running Android 10 (Go Edition), designed for basic tasks. Its key features include a removable battery and Face Unlock. However, users frequently encounter significant software problems, most notably an unreliable Face Unlock feature that often fails, severe performance lag due to its older MediaTek MT6580 chipset, and poor battery life. For users experiencing these frustrating issues, or those needing to recover from a bootloop, flashing the official stock firmware is the definitive solution to restore the device to a clean and functional state.

ℹ️ Important Note:
This phone is powered by a MediaTek chipset and requires the SP Flash Tool to install the firmware. All provided firmware is for the EEA (European) region. This process will completely erase all your personal data.

⚠️ Prerequisites: Before You Begin

Click Here for the Essential Pre-Flashing Checklist

Backup Your Data: All your contacts, photos, and files on the phone’s internal storage will be permanently wiped.
Charge The Battery: To prevent the phone from shutting down during the update, ensure the battery is charged to at least 50%.
Windows PC & USB Cable: You will need a Windows computer and a standard micro USB cable to perform the flash.

📱 Quick Device Specifications

Device: Cubot J8
Chipset: MediaTek MT6580
Display: 5.5″ IPS (960×442)
Operating System: Android 10 (Go Edition)
RAM: 2GB
Storage: 16GB
Battery: 3100 mAh (Removable)

🛠 Required Tools & Downloads

File / Tool	Download Link
SP Flash Tool	Download Tool
MediaTek USB VCOM Drivers	Download Drivers

⬇️ Cubot J8 Stock ROM / Firmware

It is highly recommended to use the latest version (V08) for the most recent bug fixes and stability improvements.

Android Version	Filename	Release Date	Size	Download Link
10 (Go Edition)	Cubot_J8_…_V08_210414.zip	2021-04-14	1.25 GB	Download (Google Drive)
10 (Go Edition)	Cubot_J8_…_V07_210310.zip	2021-03-10	1.25 GB	Download (Google Drive)
10 (Go Edition)	Cubot_J8_…_V04_200828.zip	2020-08-28	1.25 GB	Download (Google Drive)

Quick Steps to Flash Cubot J8 Firmware

Download and install the MediaTek VCOM drivers. Extract your chosen firmware ZIP file (e.g., Cubot_J8_..._V08_210414.zip) and the SP Flash Tool on your PC.
Launch flash_tool.exe. Click the “Scatter-loading” button and select the MT6580_Android_scatter.txt file from the extracted firmware folder.
Ensure the flashing mode in the dropdown menu is set to “Download Only.”
Power off your phone and remove the battery. Click the green “Download” button in SP Flash Tool, then connect the phone to your PC via USB cable (without the battery).
The flash will start automatically. Once you see the green checkmark pop-up, you can disconnect the phone, re-insert the battery, and power it on.

For a more detailed, step-by-step guide on this process, please refer to our main tutorial:
👉 Full Tutorial: How to Flash MediaTek Firmware with SP Flash Tool

❓ Frequently Asked Questions (FAQs)

Q1. The Face Unlock on my Cubot J8 is very unreliable. Can this be fixed?: Yes, this is the most common complaint for this model. Flashing the latest firmware (V08) is highly recommended, as it often includes improvements to the face recognition algorithms. A clean installation will also fix any software glitches causing the feature to fail.
Q2. My phone is extremely slow, even though it’s running Android Go. Will flashing help?: Yes. A clean flash will restore the phone to its original factory performance by removing all software clutter and junk files. However, the MT6580 is an older chipset, so it’s important to manage performance expectations and stick to lightweight “Go” apps.
Q3. My phone’s battery doesn’t last a full day. What’s the problem?: Poor battery life can be caused by software bugs or rogue apps. Flashing the latest stock ROM ensures you have the most optimized power management settings from the manufacturer. After flashing, monitor your app usage to identify any specific apps that are draining the battery.

🔧 Device Troubleshooting

The phone is not detected by SP Flash Tool: The removable battery simplifies this. Ensure the VCOM drivers are installed, click “Download” in SP Flash Tool, remove the battery from the phone, and then connect the phone to the PC without the battery inside. This is the most reliable method for the MT6580.
After flashing, the phone is stuck in a bootloop: Let the phone sit for at least 15 minutes on the first boot. If it is still stuck, you must boot into recovery mode (Power + Volume Up) and perform a “Wipe data/factory reset” to clear any old data conflicts.
I get a “PMT changed for the ROM” error in SP Flash Tool: This error means the partition layout is mismatched. To fix this, change the flashing mode in SP Flash Tool from “Download Only” to “Firmware Upgrade” and try the process again.