Phone boots into firmware update

I recently updated my lg G3 ( Google patch update named Aug-18-2015 etc) and it started to malfunction with resets, crashing and eventually got it stuck in boot loop. Then it booted into a green screen that said "demigod crash handler/tz crash" thrice. Instead of a hard reset I decided to using the lg mobile support tool to fix it. During the upgrade recovery my phone went into download mode/firmware update. I could see the progress bar moving and then get stuck and my mobile would switch off. Took out the battery, disconnected and reconnected the phone and tried the process all over again but in vain. I repeated this at least 8 times and eventually gave up. Now my phone is basically useless and only boots into firmware update. Hard reset doesn't work either. Can somebody please help me fix this?

Android version : 5.0
Kernel: 3.4.0
Firmware : v20t-ame-xx