Default [Q] Problems with Download mode

Right, so I'm pretty new to rooting but I figured I'd give it a try last night. I managed to root my G2 (D802) just fine and then tried to get TWRP. This is where it all started to go wrong. I was pushing the files via ADB like the guides said but it wouldn't work, so I took someone's advice to install it via an app called Freegee (I think that was the name). But anyway, it said it had installed and so I turned my phone off to check but when it was turning back on, it got stuck at the LG logo. I then spent all night trying to get the phone working again as I didn't have any backups or ROMs installed on my phone to flash from. I eventually managed to adb sideload a rom and get it working but now I want to unroot but I can't because Download mode just stays on the little rectangle with 4 blue dots that you get when you first turn it on in that mode. Any ideas on how to fix this?