Alright, now later down the line the phone received an OTA update (probably Kitkat). When the phone "booted", the LG logo flashed on the screen and then stayed black (the backlight was still on). If I hold the power button+volume down, the phone will just reboot. Without really being able power down the device, it seems I cannot get into download mode. Also, if I hold down power button+volume down for a long time, the notification LED will blink red (5 times *stop* 5 times...) until I let go.
Eventually I tried the power button+volume down button multiple times, pressing it in different timing intervals and managed to get it into factory reset mode! I followed the prompts but alas the phone will still not boot normally and the screen backlight is still on.
I hope this is the right forum, I need help fast.