My LG Ultimate 2 won't turn on.

[AC Question]

My LG Ultimate 2 recently had no service. My service time didn't end until 9/25/16. I couldn't text, make phone calls, or use data. I didn't really know what to do. That was about a month ago. But recently, my phone would freeze, and I would have no choice but to take my battery out and put it back in. Up until a week ago, one time I put the battery back in, and it would just load on the blue tracfone logo. It would just stay there and not turn on. Now, whenever I turn my phone on, it just shows the LG Life's Good message with this message on the upper left corner: ERROR boot certification verify, Secure booting Error, Cause: boot certification verify. And now it just does that on repeat. Constantly. It doesn't even load to the blue tracfone logo. If anyone else had this problem and got it fixed, please help me!