Default Black Screen Cant enter fastboot, Recovery or download mode.

Hey guys.
Problems began when I flashed CM11 over stock 4.1.2 on my Optimus G and later decided to go back to stock again.
Everything was done witouht problems using nand back up with CWM
But later I realiced that M5 was out and, once again tried to install it. Dont know what happen but while device was turning on, trying to go into fastboot, recovery or dowload mode screen I get BLACK screen only. The phone was was working at this time

But later I tried to install another recovery with Rom Manager and after succes mesage I reboot device and now I have nothing more that a black screen. The device is recognized when pluged in.

Please what can I do

Thanks