ok turn off, keep pressing volume up, power cord in whilst pressing, do you get download mode? if so reflash kdz or update recovery via lg mobile suite.
if that doesnt work, try installing drivers on computer again, reboot computer, turn on phone connect, check if you can adb to it, then there might.be some how to adb recovery on it, as well as pushing a rom on it. maybe.
did you check twrp size before putting it on? also was it correct version for your phone version?
send from the jungle