Sony's concept for Android 6.0 Marshmallow has been very well accepted among testers as survey showed a huge percentage of them would not want it to end. When the concept becomes official, it shall be rolled out to Xperia Z2 and Xperia Z2 Tablet very soon.

Sony Xperia Z2 and Xperia Z2 Tablet devices are poised to receive the Android 6.0 Marshmallow update in the first quarter of 2016 as announced by the Japanese giant last year about the upgrade's estimated time of arrival (ETA) to its devices. Despite update delay rumors of Sony, this year's quarter is not yet half-way through, so the company still has leeway to push the update within the target time frame.

Sony together with Samsung are the only device manufacturers that have not been able to release official Marshmallow builds yet. LG, HTC, Google, Huawei, Xiaomi, Asus and Lenovo have already begun releasing updates to at least a few of its devices. HTC and Motorola led the Marshmallow race with four devices each being updated.

Among Sony's lineup, the most recent flagship phones getting the update first are Xperia Z5 Premium, Xperia Z5 Compact and Xperia Z5. Its Marshmallow concept was tested on Xperia Z3 and Xperia Z3 Compact.

While the official build has not been made available to Xperia Z2 and Xperia Z2 Tablet yet, a custom ROM based on the Android Open Source Project (AOSP) was developed to get the update unofficially.

To install it, here's a quick go-to instruction:

1. Flash this boot via Fastboot Sirius image.

2. Boot to Recovery Mode. To do this, shut down device then restart it. As the LED lights turn purple, simultaneously press volume up and down buttons.

3. Factory reset device if using LP or other custom LP ROMs.
4. Download ROM .
5. Flash SYSTEM.img and BOOT.img from ROM via FASTBOOT.
6. Flash again first Boot.IMG

6.1 Flash this Boot via Fastboot again (don't use boot.img from ROM) Sirius Image
6.2 Root Direct Download
6.3 Reboot to recovery (like in STEP 2) than flash SUPER-SU.zip 
6.4 Boot to fastboot and flash back BOOT.img from ROM

7. Boot to Recovery Mode. 
8. Flash gapps zips here.
9. Flash again Boot.IMG Form ROM.

10. Restart the device.

 The ROM offers fixes on audio, video, Bluetooth, microphone, camera, brightness and so many more.