Essential Instructions to Install Custom Recovery on Galaxy S2

A custom recovery allows to install a custom ROM with adb sideload by disabling signature verification. This tutorial is for Galaxy S2 on OSX. The Android fastboot is not applicable for Samsung devices.

Prep.

1. install the Android SDK and set PATH to platform-tools/
2. download and install Heimdall to flash
3. download CWM for Galaxy S2 AT&T or others models here

Instructions

1. unzip CWM to have zImage in the current directory
2. turn off the device
3. press Power + Volume Down + HOME to turn on the device
4. press Volume Up to continue to enter the Download mode
5. type the following command to flash with the custom recovery
   
   $> sudo heimdall flash --KERNEL zImage --no-reboot 

NOTE

• The custom recovery allows to install a custom ROM with adb sideload.
• If failed with error messages, turn off the device and retry.