To get out of the Download mode, just press and hold the Power button till you see the LG logo on the screen. Boot LG G3 /G2 into Recovery Mode Turn off your device. For many, entering download mode on the LG G3 probably isn't a big deal. But if you've rooted and are looking to unroot your LG G3 for an OTA, or to send back to your carrier/manufacturer, etc. Search for the Quick Boot app and download the same. Install the app. Open Quick Boot and select “Recovery”. Wait while your LG G3 will be rebooted into recovery mode.
I will try my best to explain myself, since english is not my native language. Here we go.
I bought a second hand LG G3 (about 8 months of usage) 1 month ago, and everything worked just fine; the cellphone ran perfectly, lovely resolution, good display, battery life, etc. 3 days ago, however, I started having some problems with my camera, some functions didn't work right, and it didn't focus properly. Therefore, I decided to factory reset it. It was during that proccess, when I accidentally dropped the phone, causing the battery to fall out, interrupting the reset proccess, of course. This apparently caused a soft brick, since all I see when I turn on my phone is the LG logo indefinitely. I read in a XDA forum that In order to unbrick it, I had to follow some steps, and one of them dictated that I had to enter into download mode, which according to the forum was as easy as pressing the up button, connecting the usb and Voila. As you can expect, I did everything they told me, but nothing happened. I tried everything; connecting to a 2.0 and 3.0 usb port, using native usb cable and others too, I've tried on several computers, all possible combinations of buttons, but it seems that I'm screwed. I'm not a pro with this kind of stuff, but it seems that all I need to do is to enter download mode, and PC suite (the program I'm using) will do the rest. The worst part is that I don't have a replacement, so if can't get to fix this phone I'm double screwed. Thanks in advance, hope I made my point.