Didn't bother to read documentation and ended up bootlooping your LG G7 trying to flash roms?
Since LG engineers decided it would be a good idea to not include a key combination for emergency shutdown and instead reboots your device every time you soft or hard reset, here are a couple undocumented key combinations you can use to rescue your bootlooping LG G7.
The usual method to boot into bootloader is to insert a USB connected to your computer while holding down the Volume Down key on your powered off LG G7. But you can't power down your phone while it's bootlooping.
Instead, you can: