I found that my Verizon phone (Kyocera flipphone model E4810) has decided to self brick in March of 2025. Why do I say self-brick? I haven't used this phone with any phone service for over a year now. Since I still own the phone I used it for such things as MP3 playing, clock, etc. Worked fine yesterday when I used it for that. Today I go to boot it and it is stuck in the Kyocera screen loop and the OS won't open. Nothing environmentally was the cause. And it was in airplane mode and not connected to any wifi. So it looks like off the the landfill. Great use of raw materials and manufacturing. I am guessing that Verizon in conjunction with Kyocera agreed to an functional expiration date for it if it is not used for Verizon service. I'll never do business with either company again.
It's clear that this company practices planned obsolescence; they probably included a time bomb within the firmware. If you care enough, attempt a hard reset or flashing new firmware, but dismal likely suggests it's a mandatory kill switch. Stay away from Kyocera and Verizon from now on.