I am, as always, not responsible for what you do with your device. Do it on your own risk.
I will however not explain on how to set up fastboot on your PC. There are tons of tuts out there on xda, just search for it
NOTICE: You need an unlocked bootloader for this
Screenshots will be added later, 'cause my lappy is compiling right now and i thought i could use the time to write this so just wait a bit
Now, lets begin with the fun, shall we?
Fastboot is usually quite easy to use. But if you went searching for a tut on the web, you might have noticed that it doesn't work the way it should on your device.
That's because LG messed something up in the bootloader, but let's don't worry about that now, it does work nontheless
Fastboot is "a part" of the bootloader. This means, neither the kernel (boot), nor the recovery gets booted.
That gives you the ability to flash, but also boot kernels/recoveries. And yes, i meant booting, without really flashing it
Now we need to get into fastboot mode:
And this is (one of) the point(s) where LG messed up. The usual command is "adb reboot bootloader". But this command does not work on your device the way it should.
It gets you into a kind of fastboot mode, but you can't flash anything, because it says the bootloader would be locked, even tho it isn't.
The working command is
adb reboot oem-unlock
It will lead you to the working fastboot mode
now we're in the working fastboot mode. To check if you've set up fastboot correctly, type
It is recognized? good. so now we might want to check the status of our device (BL unlock state, serial number,...).
fastboot getvar all
If everything's fine, you might want to...
In order to flash something, you need the appropriate image. For kernels it's mostly "boot.img"
The command to flash something via fastboot is in general
fastboot flash <partition> <filename>
So you type
fastboot flash boot test_boot.img
Of course you can flash other partitions, too, like system, data, cache, recovery...
After a flash, it is wise to clear the cache, or even your /data partition...
Deleting a partition
You don't need a recovery to wipe a partition, just use fastboot
The general command is
fastboot erase <partition>
fastboot erase cache
So now we've flashed what we wanted to, wiped the needed partitions, but how do i..
Get out of fastboot
This is as easy as getting in just type
So press the power button for at least 10 secs. Now your device will reboot into recovery (!?)
then just tap reboot system now and be happy )
now your device will boot up normally (except your kernel/system.... has a bug of course )
for more help, just type
Bricking the device
nah, just kidding