[Desire 820 General] YBS14881:
Hi, friends...

Now time comes to upgrade your phone to Marshmallow 6.0, So we have a Marshmallow Ruu, we don't have to go through the Ota update method, So quickly match your phones specifications to following and get prepared to upgrade :-

Notice:(Updated on 14/09/2016) Who had problems with this Ruu during flashing and after flashing, Please check Hotboot version and update from following link if need. (3.17.720.3)

https://mega.nz/#!w8hB3DjY!NyCbl-YMv04qQft1hJtFyz7VDZKKYyQzV8RMWLYhFpw

How to flash This Files?

Copy to adb fastboot folder.

Run command*

fastboot oem rebootRUU

fastboot flash zip filename.zip

fastboot reboot

Note:*Before write your bootloader must be locked state.(Updated.14/09/2016)

* ***NOTICE :- THIS TUTORIAL IS ONLY FOR INDIAN VERSION, Read it carefully and proceed through same as described hence I am not responsible for any damage or brick of your phone.PLEASE MATCH THE FOLLOWING...

* * * * * * * * * * * **MODEL CODE * * * * * *:- A51 DTUL (820U) Dual Sim.

* * * * * * * * * * * * CID NO * * * * * * * * * * * *:- HTC_38.

* * * OK, If your phone matches above configuration than consider following two methods as your phone is stock position or rooted.

* * * * * * **First Method*:- This method is for stock rom phones, who have locked bootloader with stock recovery but update problem or no software update tab in setting of phone. ( Locked bootloader & Non-rooted )

* * * * * * **

* * * * * * * *1) Charge your phone upto 80% minimum.

* * * * * * * *2) Backups your contacts, apps+data,sms,bookmarks with any backup app.Move your important data from internal storage to sdcard.

* * * * * * * *3) Download This*https://mega.nz/#!0ww2WbYI!bTJ-XmEZem9Et-Xekysw1I00rCkXWEp0SpN5x5It1QgMarshmallow*Ruu.

* * * * * * * *4) Rename it to 0PFJIMG.zip,*Note:ofirst alphabet is number zero (0) not O for orange.

* * * * * * * *5) Place the file in root path of external sdcard.

* * * * * * * *6) Power off your phone, after 10 second press volume down button along with power button to boot into bootloader.

* * * * * * * *7) In bootloader, the file automatically detected and start flashing.Now don't mess with phone, it will take half hour to fully flashed.

* * * * * * * * * **

* * * * * * * * * * **Enjoy the Marshmallow!!

* * * * * * * * *Second Method*:- This method for unlocked bootloader, modified and rooted phones, So first we have to relock bootloader before update.

* * * * * * * * ***1) Charge your phone upto 80% minimum.

* * * * * * * * * *2) Backups your contacts, apps+data,sms,bookmarks with any backup app.Move your important data from internal storage to sdcard.

* * * * * * * * * *3) Relock bootloader with this easy*https://mega.nz/#!Rl5HlTQa!9PQUbo2VsLluh_NKG7btv0SGSCUH0wT3_gXofDecyX4software, or you can use fastboot method.

* * * * * * * * * *4)*Download This*https://mega.nz/#!0ww2WbYI!bTJ-XmEZem9Et-Xekysw1I00rCkXWEp0SpN5x5It1QgMarshmallow*Ruu.

* * * * * * * * * *5) Rename it to 0PFJIMG.zip,*Note:ofirst alphabet is number zero (0) not O for orange.

* * * * * * * * * *6) Place the file in root path of external sdcard.

* * * * * * * * * *7) Power off your phone, after 10 second press volume down button along with power button to boot into bootloader.

* * * * * * * * * *8) In bootloader, the file automatically detected and start flashing.Now don't mess with phone, it will take half hour to fully flashed.

* * * * * * * * * *

* * * * * * * * * * **Enjoy the Marshmallow!!

Press Thanks button if get helped.