2014 flagship smartphone OnePlus One users have reportedly begun receiving a new firmware upgrade notification.

The new update (build number: YOG4PAS2QL) is 18MB in size and is said to come with bug-fixes and security upgrades (probably related to Stagefright glitch).

As of now, the update is officially available only through OTA (Over-The-Air), but it will take some time to reach all the corners of the world as this process is being carried out in phases.

If patience is not your strongest suit, then you can try manually flashing the firmware on the OnePlus One.

Prerequisites (things to remember before installing Custom ROM)

  • This new Cyanogen OS 12.1 Android 5.1.1 Lollipop update has to be installed only on OnePlus One aka Bacon models only; if tried on other devices, it might get bricked [To check your device model: Go to Settings >> About phone >> model number]
  • Make sure the device is rooted (Bootloader unlocked) before going forward for custom ROM installation. [How to unlock Bootloader]
  • Though installing custom ROM improves the device's performance and UI experiences, it makes the company warranty void and they will no longer be liable to provide updates in future [users can restore warranty by flashing the device with stock-ROM].
  • Installation of custom ROM requires clearing of memory in the smartphone, so make sure to back all the data by installing Clockwork Mod (CWM) Recovery/ TWRP in the smartphone.
  • Users make sure they have installed USB drivers on the PC, or else your device (OnePlus One) will not be recognized by the computer.
  • Make sure your device has more than 80 percent battery, or else there is a chance of smartphone getting temporarily bricked if the installation process is interrupted mid-way.

[Disclaimer: This procedure is very technical and should be performed by a person with sound knowledge of rooting (or manual software installation) Android devices. If the step-by-step installation process is not followed properly, there are chances of the smartphone getting bricked or being permanently irreparable. IBTimes India cannot be held responsible for any damage or claims from readers if the procedure does not yield the required results or if the smartphone is bricked. Hence, users are advised to proceed with caution.]

Downloadable files:

Tutorial: Step-by-step installation procedure of Cyanogen OS 12.1 Android 5.1.1 Lollipop ROM on OnePlus One (aka Bacon) model:

Step 1: After downloading new Cyanogen OS 12.1 Android 5.1.1 Lollipop update in to your PC, connect OnePlus One to PC via USB cord

[Note: Before plugging the phone to the computer, be sure that you have installed USB driver software, if not, click HERE to download the firmware]

Step 2: Place Cyanogen OS 12.1 (YOG4PAS2QL) zip file into the phone's internal storage memory. [Note: Users are advised to paste the .zip file in the storage root folder, not in any other folder.]

[Note: Before users' begin installing the custom software, be sure that the device must have rooted and has installed TWRP tool.]

Step 4: Turn off the device and disconnect from the PC.

Step 5: Perform the regular Recovery Mode sortie by press holding 'Volume (Down)' and 'Power' buttons.

Step 6: After entering the RECOVERY mode, clear the phone memory, by hitting 'Wipe' option

[Note: use 'Volume' keys to navigate and 'Power' button to select options, while operating under Recovery Mode]

Step 7: Return to the main menu and tap 'Install'. S

Step 9: After going in to the 'Install' section, select the file you download from the PC and initiate installation by tapping 'Swipe to Confirm Flash'

Step 10: Once done with the flashing, re-start the OnePlus One by selecting "Reboot system"

Now, your device (OnePlus One) will take a few minutes to complete the booting process.

Users then head to 'Settings' >> select 'About phone' to confirm the installation of Cyanogen OS 12.1 Android 5.1.1 Lollipop [YOG4PAS2QL] ROM.

[Credits: OnePlus Forum member Chandan.Napster]