As a rep of this site, I MUST take this opportunity to invoke the typical disclaimer...you can back out of this if you want. You're willing to assume all risk blah blah blah.
I have NOT done this procedure myself but I HAVE seen this done and it has worked to restore download mode to the LG G2. So if you're cool with all that...
...here's what we do. I would just as soon house those 7 images in a folder so they're all in one confined spot. Probably not necessary but I feel better about it. Maybe create a folder on your desktop and call it android. Once done, place the 7 .img files into that folder. Then fire up terminal and cd to that android folder.
Just to be sure, we're still a go, issue the fastboot devices command first from that locale. If it shows up as before, we're ready. Very important to maintain a constant connection with the phone to Mac from here forward. Next issue these commands, waiting for each to complete before starting the next:
fastboot flash aboot aboot.img
fastboot flash boot boot.img
fastboot flash laf laf.img
fastboot flash recovery recovery.img
fastboot flash rpm rpm.img
fastboot flash sbl1 sbl1.img
fastboot flash tz tz.img
Once all the flashes are complete, go ahead and disconnect the usb cable from the phone and long press the power button. If it reboots, then long press the power button again until the phone is completely off.
Once it's off, try now to enter download mode and see if you have it. If all went well, you should.