How to Completely Downgrade Zenfone 3 Max ZC553KL to Marsmallow

Around 2022, there was a software update for Zenfone 3 Max to Android version 8.0 (Oreo). Although the update includes a variety of new features, but not with battery optimization, many think that Oreo is still as wasteful as Nougat.

Meanwhile, many people think that the Android version of Marsmallow more battery saving than the version above. For that, here I want to explain how to downgrade to version 6.0 (Marshmallow) safely.

Ingredients Before Downgrade

Prepare a computer or laptop that will be used to flash the firmware. And after that turn it on USB Debugging on the cellphone, so that later it can be detected in ADB.

And here are some things that need to be downloaded on the computer:

  • Minimal ADB and Fastboot.

  • Marsmallow version firmware (

Sorry, the Second Blog site does not provide the file, so you can search for it on Google.

And if you have downloaded it, please extract fill the firmware file to the Minimal ADB directory.

Zenfone ZC553KL Downgrade Steps

Please follow the tutorial below correctly so that no errors may occur. You can also listen to the tutorial first before practicing it. So when there are things that are not understood, it is highly recommended to comment to get help.

Also make sure before doing it, the battery on the phone is still above 50%. Because if the battery runs out in the middle of the process, it can cause the phone to freeze.brick.

  1. Connect the phone to the computer with a USB cable.

  2. Open Command Prompt in the Minimal ADB directory. Then type the command adb devices

  3. If the phone is already connected in ADB, please use the command flashall.bat to start flashing.

  4. Instantly the phone will enter bootloaderplease wait for the process to finish.

  5. If it’s finished, surely the phone will boot.

  6. And done. Now the phone is back to the Android version of Marsmallow.

The first boot will take a little longer, about 5 minutes, so please wait. And after that please check the Android version, it must have been successfully downgraded to 6.0.

IMEI Null or Missing Solution After Downgrade

Don’t worry, this is just a normal problem. All you need to do now is to download the OREO version firmware and then fetch the file named NON-HLOS.bin and move it to the Minimal ADB folder.

If so, please connect the phone to the computer with a USB cable. After that enter fastboot mode with the following command:

adb reboot-bootloader

After that use the following command to delete the MODEM file on the system:

fastboot erase modem

Next is the installation process, use this command:

fastboot flash modem NON-HLOS.bin

And the last step is to reboot the phone, you can use the following command:

fastboot reboot

Please check the IMEI, definitely not now null again and of course the signal on the SIM card will appear immediately. So the conclusion is just taking the modem file from the OREO firmware. And this will not affect to other performance.

Also read: How to Fix Android Not Detected in ADB

Video Recorder Problem Solution After Downgrade

Another problem is the video recorder that doesn’t work properly. So while using it, the camera app suddenly force close and video recording is cancelled. But don’t worry, because there is a solution for this and the solution is almost the same as the method above.

So please take the file named adspso.bin on the OREO firmware. Then move that file in the Minimal ADB folder.

Then connect the phone to the computer until it connects in ADB, then please enter the bootloader.

On the bootloader, use the command below to delete the current DSP:

fastboot erase dsp

Next is the installation process, use the command below:

fastboot flash dsp adspso.bin

The last stage, please reboot and try the video recorder again. It should now be normal and the camera app won’t force close anymore.


The problem during the downgrade process that I experienced was losing IMEI and also video recorder which doesn’t work, but it’s back to normal with the above method. And so far nothing bugs else happened.

For the Marsmallow version of the firmware, it has been removed on the Acer website for the Zenfone ZC553KL series, so alternatively, please look for the firmware provider websites scattered on Google.

At this point, do you have any other questions after listening to the tutorial above? If there are any obstacles or difficulties when you want to do it, please say it in the comments column below, and I will help to make it easier.

Hopefully useful and good luck