Oneplus: Steps to rollback to CM11
Steps to rollback to the stable CM11 in Oneplus one
/** PLEASE MANUALLY BACK UP YOUR DATA TO YOUR PC AND SYNC YOUR CONTACTS TO GMAIL CONTACTS (http://androidfact.com/how-to-backup-android-contacts/) **/
** ALL DATA WILL BE LOST **
Files to be downloaded :
1. Google usb driver : http://developer.android.com/sdk/win-usb.html
2. Android SDk : http://developer.android.com/sdk/index.html#download
Scroll down to SDK TOOLS ONLY and download installer_r24.2-windows.exe
3. Twrp custom recovery tool : https://dl.twrp.me/bacon/
download version 2.8.6.1 (latest version)
4. CM11 firmware : https://drive.google.com/folderview?id=0B98G0KTJwnBFRGhZeUNpMEI4ajg&usp=drive_web
download cm 11 firmware
5. CM11 official rom : https://www.androidfilehost.com/?fid=95916177934527555
PROCEDURE:
Step 1 : Installing adb and fastboot drivers
Installing this drivers allows you to access your phone from your PC command prompt terminal.
Use the google usb driver that you have downloaded.
Step 2 : Unlocking bootloader and installing custom recovery
Install the Android SDK and Install the following packages (there are a total of 4 packages):
– Tools > Android SDK Tools, Android SDK Platform-tools
– Extras > Android Support Library, Google USB Driver
After installing the SDK go to C:\Program Files\Android\android-sdk\platform-tools
And in this window press shift + right click mouse button, you should see a option OPEN COMMAND WINDOW HERE select it.
To confirm that the above steps are indeed working, open a command prompt window and enter the following command in the terminal:
adb version
If it displays “Android Debug Bridge version x.x.xx” it is working. If it is gives an error saying that adb is not a recognized command, it has not been successful. Carefully repeat the steps above if this is the case. Close the command prompt window when you are done.
Now lets unlock bootloader
Unlocking Bootloader: Opens the door to the internal memory of the device to be written on to.This allows you to flash images onto the main partitions of the phone
->Turn the phone off. Then boot it into fastboot mode by holding volume up + power. The phone will display “fastboot” text indicating that it has successfully entered fastboot mode.
->Plug the phone into your PC.go to C:\Program Files\Android\android-sdk\platform-tools And in this window press shift + right click mouse button, you should see a option OPEN COMMAND WINDOW HERE select it and type
fastboot devices
This command will list the connected devices. If your phones serial number shows up you are good to go and may continue. If the phone is NOT listed this indicates that your drivers are not installed correctly. In order for you to continue you must fix your drivers so that your phone is listed under fastboot devices.
If the phone has been recognized by the command above, proceed to unlocking the bootloader with the following command:
Remember that this step will wipe EVERYTHING off the phone
fastboot oem unlock
After the above command has finished excuting, run the following
fastboot reboot
The phone will reboot. Wait until the phone has fully booted up into android, then adjust the following settings on the phone:
USB Debugging – On your phone go to Settings > About phone > Tap on Build number 7 times. This will enable Developer options. Now go back to Settings > Developer options > Enable USB debugging
Disable CM Recovery Protection – On your phone go to Settings > Developer options. Then disable the ‘Update recovery with system updates’ option.
Close the command prompt window and proceed onto the next section of the guide.
Installing a Custom Recovery
Turn the phone off. Then boot it into fastboot mode by holding volume up + power.
Rename the recovery file that you downloaded above to twrp-recovery.img .U need to name the twrp file as twrp-recovery.img and not as recovery.img and then run this two things in terminal
fastboot flash recovery twrp-recovery.img
the above command flashes and then
fastboot boot twrp-recovery.img
it boots into recovery from fastboot directly, please note after flashing do not reboot and run this commands back to back.
Now that u are in custom recovery, reboot your phone.
Step 3 : Installing firmware and the OS itself
Here there are two steps :
1. Installing firmware by flashing it using TWRP tool
2.Installing the rom in the FASTBOOT mode using ur PC
Copy the cyanogen firmware file ( 28 MB ) to your phone please remember the location, it is better to copy it directly into root folder.
Now copy the CM11 Rom ( 520 MB ) to C:\Program Files\Android\android-sdk\platform-tools and extract it there using winzip or 7-zip any such tool.
Shutdown your phone.Reboot into twrp recovery by pressing volume down + power.
In twrp recovery
1)Select WIPE->swipe to factory reset and then home
2)Select INSTALL->browse to firmware file ,select it ->swipe to confirm flash
thus the firmware is flashed, for newbies here is video of how to use twrp tool to flash though this video has no relevance w.r.t our scenario it shows how to use twrp.Please see the entire video in particular
After flashing the firmware,turn off your phone and boot into fast boot mode
Now go to C:\Program Files\Android\android-sdk\platform-tools where you have extracted the CM11 rom , hold down shift + right click in the folder with the files and click “open command line here”
Type in all these commands in order one at a time , back to back(some of them may take some time so be patient), your phone must be in fastboot mode (Power button + Volume up) and must be plugged in to your computer:
fastboot flash modem NON-HLOS.bin
fastboot flash sbl1 sbl1.mbn
fastboot flash dbi sdi.mbn
fastboot flash oppostanvbk static_nvbk.bin
fastboot flash aboot emmc_appsboot.mbn
fastboot flash rpm rpm.mbn
fastboot flash tz tz.mbn
fastboot flash LOGO logo.bin
fastboot flash boot boot.img
fastboot flash cache cache.img
fastboot flash recovery recovery.img
fastboot flash system system.img
fastboot flash userdata userdata.img (or userdata_64G.img)
fastboot reboot
AND VOLA you’ve successfully rolled back to CM11 
If you follow this process/steps then you will not BRICK your Oneplus one because you’re doing the right order
1)FLASHING THE FIRMWARE FIRST AND
2) Flashing WITH ROM
you may have those single click bat files but they did not work for me but I am 100% sure that the above procedure should do the trick.
References :
https://forums.oneplus.net/threads/…oader-install-custom-recovery-and-root.64487/
https://forums.oneplus.net/threads/tutorial-flashing-a-factory-image-from-scratch.142870/
http://forum.xda-developers.com/oneplus-one/help/faq-oneplus-one-frequently-questions-t2895136