Same issue here.
Happened yesterday around 2pm. Plugged my V10 into my computer (just upgraded to windows 10 if thats a relevant detail) and waited while windows detected and installed the USB drivers. About 5 seconds in and my V10 goes dark. Thought thats weird and try the power button, but get nothing. Pull the battery, reinsert, and try to power up only to get the damn LG screen boot loop.
I did some testing with having the phone plugged into the wall outlet, plugged into the computer, and not plugged in to anything to see if it made a difference. Oddly enough, when connected to my computer the phone would fully boot (slower than usual), but after about 15 seconds of have it fully loaded the phone would just turn off again (and would need a battery pull to try and turn it back on)
I tried leaving the battery out for hours, tried leaving it plugged into the wall for hours, and I tried to get into recovery mode, but it wont load.
Have not had it for a year yet so its still covered by LG. Did all the paperwork online so I printed a return label today and will be sending it in for repairs.
Frustrating..... now I'm back to my note 3 which still works flawlessly.