Exclamation [Q] Secure Booting Error! Cause: boot certification verify

Hello all,

Well, it's here... Unfortunately my phone got bricked last night

Can't boot into main screen and can't go to download mode anymore. The cause is, my phone was stuck when upgrading firmware and there's nothing to do about it except remove the battery, and then, BOOM!... "Secure Booting Error! Cause: boot certification verify"

Any LG G3 users here already experienced this problem?

I followed the solution on LG G2 sub-forum, but my ubuntu doesn't detect the port, although Windows recognized it.

If this happens to your G3 and you solved it, please share your experience

Thanks
♥♡ Beby Chaesara Anadila ♡♥