How to do with not detected Download Mode Lg Android phone?

[AC Question]

i have flashed custom rom on my lg optimus g e975 recently and get the "secure booting error. Cause Devices unlock! so boot success" error and i searched about it so it should be flashed stock rom which needs download mode i can get to download mode but nothing detected. my phone is in bootloop which boots to cwm recovery.in recovery its detected as "lge mobile usb modem, lg mobile usb serial port COM and lge mobile composite usb device" i tried adb used adb devices but nothing shown in the list. would be thankful for your replies.