Talking [Q] lg optimus g f180s won't start after unlocking bootloader

i bought lg optimus g f180s few days ago. i did root my device and then unlock bootloader. unfortunately the battery of my device got too low so that it can't reboot now. i tried to charge my device with stranded charger, whenever i put the charger the red notification light appears after some time for a while then white symbol of charger with charging sign appears for just a second or less and screen got black. please help me that how can i charge my device and install custom rom.