Default Download mode for unbrick after failed OTA-Flash of knock code

Hi
I tried to flash the knock code for open-devices over a rooted stock rom with custom recovery - so everytime I boot it automatically boots into custom recovery.

How do I enter download-mode to unbrick it using the offline-fix for the LG R&D Test tool? Holding volume up while plugging in the cable boots into TWRP and holding volume up+power also boots to TWRP..

Everything I try boots into TWRP even if it should boot to Download-Mode

SOLVED: (my problem was wrong searches within XDA and Google - "no boot after flashing knock code" isn't "LG G2 download mode doesn't working")
1. Open in TWRP:
Advanced - Terminal - Select / as folder - go to terminal

2. Enter
Code:
dd if=/dev/zero of=/dev/block/platform/msm_sdcc.1/by-name/fota
and hit "GO"

3. Enter
Code:
dd if=/dev/zero of=/dev/block/platform/msm_sdcc.1/by-name/misc
and hit "GO"

4. Back to main menu in TWRP - hit reboot -> System

now worked...