AT&T E970 fastboot is not working
I bought a unlocked and rooted AT&T LG Optimus G E970 from ebay. I tried to install CMW/TWRP recovery on it by adb and fastboot commands. When I typed "adb devices" the device model and serial number message showed on PC. But when I typed "adb reboot bootloader" or I manually press Volume+ and power key same time it couldn't be going to fastboot mode anyway. It just going to Android system. What is correct method and how do I do to get it into fastboot mode so that I will able to install recovery package? Is there any way to check bootloader? However, I read some different instrutions online for manually rebooting device to fastboot mode. I don't know what is right instruction for my phone. Thanks a lot!