Why isn't my phone getting past boot animation?

[Android Central Question]

Hi I have an LG Optimus LTE 2. The model is LG-F160S. I flashed in a Cyan MOD in the phone a couple of months ago and it was working just fine until I had a problem loading the music app. I rebooted my phone as the phone got to the LG logo screen, when on the top left corner of the screen, it said in small words: " Secure booting error! Cause: Device unlock! So, boot success!" And then it took about 5 minutes to get to boot animation. And after, I couldn't get past it. I tried again after factory resetting but in recovery mode it said: can't mount /sd card