nexus 5保留数据从android 5.0.1升级至android 5.1

首先: adb reboot bootloader,进入fastboot mode，

A. fastboot flash bootloader bootloader.img
(if it isn’t called bootloader.img, use the actual file name)
B. fastboot flash radio radio.img
(if it isn’t called radio.img, use the actual file name)
C. fastboot reboot-bootloader
D. fastboot flash recovery recovery.img
E. fastboot flash boot boot.img
F. fastboot flash system system.img
G fastboot reboot

(我只刷了recovery，boot，system. 不必进行以下OTA步骤)

其次:进入recovery mode，

adb sideload your_ota_package.zip

最后:root，执行

1. Download the SuperSU file you need from here.
2. Download the Android SDK for Windows here.
3. Download the fastboot file for Windows here and extract the folder in the  android-sdk-windows\platform-tools directory.
4. Connect the Nexus 5 to the computer with the USB cable.
5. Transfer the SuperSU zip file over to the internal SD card of the phone (without unzipping the file).
6. Power down the phone.
7. Download the ClockworkMod recovery file.
   – save it to the same /platform-tools directory.
8. Boot the Nexus 5 in fastboot/bootloader mode by holding down the Volume Down and Power buttons.
9. Navigate over to the /platform-tools directory and right-click any blank white space and hold down the Shift key. Now choose to open the Command prompt.
10. Type the following command:
11. fastboot flash recovery recovery-clockwork-touch-6.0.4.5-hammerhead.img
12. Now select the Recovery options from the fastboot menu.
13. You should now be in the custom recovery mode.
14. Scroll down the list until you see “install zip” and select the option.
15. Now select the “choose zip from SD card”.
16. Search for the SuperSU file in your internal memory.
17. Confirm you wish to install the SuperSU file.
18. Wait for the installation to complete before going back to the main recovery menu and selecting the “reboot system now” option.

refer: http://dottech.org/176621/how-to-root-nexus-5-in-lmy47d-android-5-1-lollipop-for-windows-guide/#fpdhWWxrMxLCEJE5.99