But then, I went into TWRP recovery and decided to wipe it clean (Advanced, wiped all partitions including system and Internal Storage) and flash again, something bad happened. The phone will not finish booting.
The phone will boot up with the standard LG logo for about a minute. Then boot into an animated, bigger LG Logo. And then it will stuck there forever. Normally, it should go into something like "initializing... 1 out of 130".
I can still enter TWRP recovery and browse the file system and even flash another ROM from OTG-USB. But none of the ROM would boot beyond the initial boot screen. Any ideas?
Edit: It seems my issue is covered here:
I had 39A and really don't want to go back to square one if I have a choice. What exactly is the Internal Storage and why even having TWRP cannot help me recover?