How to Root Micromax Bolt A40: Full Guide

Updated 6 November 2026 · Standard formula, shown below

Rooting your Micromax Bolt A40 gives you full administrative control over the Android system, letting you remove bloatware, install custom kernels, use root-only apps, and even flash custom ROMs. This guide walks you through the entire process using a PC, covering everything from unlocking the bootloader to verifying root access. Before you begin, back up your data and ensure your battery is above 70%.

What You’ll Need

A Micromax Bolt A40 with at least 70% battery charge
A Windows PC (Windows 7, 8, 10, or 11) with a working USB port
A USB data cable that can transfer files (not just charge)
Micromax USB drivers installed on your PC
ADB and Fastboot tools (Platform Tools) downloaded and extracted
An unlocked bootloader (required for most rooting methods)
Magisk APK and a stock boot.img file for your exact build number

Step-by-Step

Enable Developer Options: On your phone, go to Settings â†’ About Phone â†’ tap Build Number seven times. You’ll see a toast saying “You are now a developer!”
Enable USB Debugging and OEM Unlock: Go to Settings â†’ Developer Options and toggle on USB Debugging and OEM Unlock. If OEM Unlock isn’t visible, you may need to skip it, but it’s essential for unlocking the bootloader.
Install USB Drivers: Download and install the Micromax USB drivers on your PC. Restart your computer after installation.
Set Up ADB and Fastboot: Extract the Platform Tools zip to a folder like C:\adb. Open a Command Prompt in that folder (Shift+Right-click â†’ “Open command window here”).
Connect Your Phone: Connect the A40 to your PC via USB. On the phone, accept the RSA key fingerprint prompt for USB debugging.
Verify ADB Connection: In the Command Prompt, type adb devices. You should see your device listed as “unauthorized” first, then “device” after you accept the prompt. If it says “offline”, re-plug the USB cable.
Backup Your Data: Use adb backup -apk -shared -all -f backup.ab to create a full backup. Store this file safely on your PC.
Unlock the Bootloader: Type adb reboot bootloader to enter fastboot mode. Then type fastboot devices to confirm your phone is detected. Now type fastboot oem unlock (or fastboot flashing unlock on newer devices). On the phone, use the volume keys to select “Unlock” and press power to confirm. This will wipe all data.
Reboot Normally: After unlocking, type fastboot reboot. The phone will restart and may take longer on first boot. Re-enable USB debugging (Developer Options may reset).
Extract Boot Image: You need the stock boot.img for your exact build number. You can extract it from the official stock ROM (firmware) for the A40. Download the ROM, extract it, and look for a file named boot.img or boot.img.emmc.win.
Patch Boot Image with Magisk: Transfer the boot.img to your phone’s internal storage. Install the Magisk APK on your phone. Open Magisk, tap “Install” â†’ “Install” again â†’ “Select and Patch a File”. Choose the boot.img. Magisk will create a patched file in Download folder, usually named magisk_patched-xxxxx.img.
Copy Patched Image to PC: Transfer the patched image file to your PC’s ADB folder.
Reboot to Fastboot Again: Type adb reboot bootloader.
Flash Patched Boot Image: In fastboot mode, type fastboot flash boot magisk_patched-xxxxx.img (replace with the actual filename). Wait for the “OKAY” message.
Reboot and Verify: Type fastboot reboot. Once the phone boots, open the Magisk app. If it shows “Magisk is installed” with a version number, root is successful. You can also use a root checker app from the Play Store.

Common Mistakes

Skipping OEM Unlock: If you don’t enable OEM Unlock, the bootloader unlock command will fail with “FAILED (remote: oem unlock is not allowed)”.
Using the Wrong Boot Image: Flashing a boot.img from a different build or ROM can cause a bootloop. Always match the exact build number.
Insufficient Battery: If the battery dies during flashing, you risk bricking the device. Keep it above 70%.
Bad USB Cable: A charge-only cable won’t establish a stable ADB connection. Use a known data cable.
Not Accepting the RSA Prompt: If you don’t click “Allow” on the phone when connecting, ADB will show “unauthorized” and commands won’t work.

Tips

Always keep a backup of your stock boot.img so you can unroot by re-flashing it.
After rooting, install a root manager like Superuser or Magisk’s built-in manager to control which apps get root access.
If you plan to flash custom ROMs, make sure you have a custom recovery like TWRP installed first, but this guide focuses on Magisk only.
Use a dedicated folder for ADB files to avoid path issues.
Disable antivirus on your PC temporarily, as it may interfere with ADB drivers.

Troubleshooting

ADB not recognizing device: Reinstall drivers, try a different USB port, and ensure USB debugging is enabled. In Device Manager, check for yellow exclamation marks.
Fastboot stuck at “waiting for device”: Make sure you’re in fastboot mode (black screen with fastboot text). Install the correct fastboot driver manually via Device Manager.
Bootloop after flashing: If the phone stays on the boot logo, you likely flashed a wrong image. Re-flash the stock boot.img you backed up. If that fails, restore your backup via recovery.
Magisk app shows “Requires Additional Setup”: Tap “OK” and let Magisk reboot the device automatically. If it doesn’t, reboot manually.
OEM Unlock greyed out: This usually means the device is carrier-locked or the option is hidden. Try connecting to Wi-Fi and signing into a Google account first.
Unlock command fails with “unknown command”: Some devices use fastboot oem unlock-go or fastboot flashing unlock. Try those variants.

Frequently Asked Questions

Will rooting void my warranty?

Yes, rooting typically voids the manufacturer warranty. However, you can unroot by flashing the stock boot image and re-locking the bootloader to restore warranty status.

Can I get OTA updates after rooting?

Usually not directly. OTA updates often fail on rooted devices. You’ll need to unroot, install the update, then root again. Or you can manually flash the updated boot image.

Will rooting erase my data?

Unlocking the bootloader will wipe all data. The Magisk patching process itself doesn’t erase data, but the bootloader unlock step does. Back up everything important before starting.

Is it safe to root my Micromax Bolt A40?

Rooting is generally safe if you follow instructions carefully. The main risks are bootloop or bricking if you flash wrong files. Sticking to the exact stock boot.img minimizes risk.

Can I unroot later?

Yes. You can unroot by flashing the original stock boot.img via fastboot. Alternatively, in Magisk app, tap “Uninstall” and choose “Restore Images” if you haven’t modified the system.

What if I don’t have a PC?

Rooting without a PC is possible using apps like KingRoot, but these are less reliable and may not work on this device. A PC is strongly recommended for a safe and permanent root.

Method: the standard formula for this calculation, rounded as each result states. See how the calculators work or report an error.