How to Upgrade A850 from Android 4.2.2 to Android 5.0

Introduction

Upgrading your A850 from Android 4.2.2 to Android 5.0 can significantly enhance performance and add new features to your device. However, it's important to note that not all devices receive official updates from Google. If your A850 lacks an official update, you might need to consider installing a custom ROM. Here’s a comprehensive guide to help you through the process.

Checking for Official Updates

Step 1: Check for Official Updates

Open your A850 and go to Settings. Navigate to About Phone and then select System Updates. Tap on Check for Updates. If an official update to Android 5.0 is available, follow the on-screen instructions to download and install it.

Installing a Custom ROM if No Official Update is Available

Prerequisites

Unlocking the Bootloader

Step 2: Unlock Bootloader

Unlocking the bootloader may void your warranty, so proceed with caution. Instructions for unlocking the bootloader can generally be found on the manufacturer's website or forums. Be sure to follow the instructions carefully to avoid bricking your device.

Installing Custom Recovery

Step 3: Install Custom Recovery

Download the appropriate TWRP image file for your device. Flash the TWRP recovery to your device using fastboot:

fastboot flash recovery path_to_twrp_image

Download a Custom ROM

Step 4: Download a Custom ROM

Look for a reliable custom ROM that supports Android 5.0 for your device, such as LineageOS. Ensure the ROM is compatible with the A850.

Download GApps

Step 5: Download GApps

If you want Google apps, download the appropriate Google Apps package for Android 5.0.

Flashing the Custom ROM

Boot into Recovery Mode

Step 6: Boot into Recovery Mode

Turn off your device. Hold the Power button and Volume Up button simultaneously to enter recovery mode.

Wipe Data and Factory Reset

Step 7: Wipe Data and Factory Reset

In TWRP, select Wipe and then Factory Reset. This will erase all data on your device.

Install the ROM

Select Install in TWRP. Navigate to the location of the custom ROM zip file and select it. Swipe to confirm the installation.

Install GApps

Step 9: Install GApps

After flashing the ROM, repeat the installation process for the GApps package.

Reboot

Step 10: Reboot

Once the installation is complete, go back to the main menu and select Reboot System.

Post-Installation

Setting Up Your Device

Step 11: Set Up Your Device

After rebooting, set up your device as you would with a new phone.

Restoring Data

Step 12: Restore Data

Restore your backups if needed. Ensure you have the proper backup files before restoring.

Important Notes

Risk of Bricking

There is a risk of bricking your device, which could render it unusable. Follow instructions carefully and understand the risks involved.

Warranty

Unlocking the bootloader and installing custom ROMs may void your warranty. Consider consulting a professional if you’re not comfortable with these steps.

Conclusion

Upgrading your A850 from Android 4.2.2 to Android 5.0 can be a straightforward process if you follow the steps carefully. However, keep in mind that there are risks involved, especially if your device doesn't receive official updates. If you are not comfortable with these steps, seek help from someone experienced in Android modding or check forums like XDA Developers for guidance specific to your device.