[General Questions and Answers] ganesh3s3:
If you did something like install custom recovery on your lg optimus one and failed, you would get a black screen saying..

fastboot mode started

udc_start()

If this happens...

Relax.. Your phone is not bricked.. There are many ways to fix it... This method of unbricking should be done as a last resort because it erases all your data...

Charge your phone before proceeding even if the backlight is always on while charging..

Things required:

Kdz updater:

http://xdaforums.com/showpost.php?p=8651505&postcount=1

Stock ROM:

http://xdaforums.com/showthread.php?t=865479

USB cable, Windows PC with administrator account,LG united mobile drivers(google for it if you don't find it in the "Add or remove programs" window in the control panel)..

First disable all LGE modems under modems from Windows device manager in the Control Panel..

Make sure you have LG united mobile drivers installed.. Or just google for it..

Then press and hold both the back(return) button and the volume up button and simultaneously connect the USB cable..

The phone should light up and say Emergency mode!! in a green background.. If it goes to Emergency mode, it can be fixed... If it doesn't I'm sorry, search for an other forum or give it to the LG service center...

Now decompress the 7z file you downloaded using WinZip, WinRar etc., install msxml.msi from the uncompressed directory and run KDZ_FW_UPD.exe (With administrator rights by right clicking and selecting run as administrator).

In the dialog box, select Type : 3GQCT and PhoneMode: DIAG, select the kdz file and flash the stock ROM... It would take about 15 minutes.. If the kdz updater crashes, change compatibility mode or restart the computer and phone or do something till it works (Retry retry retry)...

For most of you it would probably say PHONE WAS NOT FOUND!.... If so, then follow all the steps said above, but this time, shake the life out of your phone after connecting the USB till the lines "PHONE WAS NOT FOUND!" stops appearing... If it does appear again retry for endless times or restart the computer or check if any modem drivers are active or try it in an another computer...

From here on, follow any one choice:

Choice 1:

Note: There is a fat chance for this choice to not work and for you to go back to the very first line of this thread...

If you want your phone to have all the data before you bricked it, just disconnect the USB when the phone shows the charge screen as if you are charging the phone while it is switched off.. (This was discovered accidentally by me so try it at your own risk :rolleyes:) After disconnecting try to power on the normal way and it should work and the phone should be like it was never bricked.. If it doesn't boot, retry flashing from the start.. If it starts and all your data is restored root it, install titanium backup and backup all your apps and data and save the contents of sdcard\titaniumbackup to your pc.. Then copy all you want in your sdcard to your pc.. Then redo all the steps without disconnecting till the kdz flasher says FINISHED.. This is because if you disconnect the usb in the middle, only half the rom would be installed which is unstable.. After installing the full rom, root it, and install titanium backup and copy all the copied content back to sdcard\titaniumbackup and restore them using titanium backup.. That's it..

Choice 2:

If you do not want the data and if you need to do a risk-free unbrick, then flash with the kdz updater and wait till it says FINISHED.. That's it..

Now that you know how to unbrick, try installing what bricked your phone again but this time in the correct way... GOOD LUCK...

AND FINALLY.... ONE MORE STEP.... PRESS THE "THANK" BUTTON IF I HELPED YOU IN ANY WAY...:p