I am seeing the same issue with boot failure. As suggested I attempted to upgrade to 2.8.1, but when checking for software updates I got an odd error. After a few attempts I thought I’d reboot the panel and try again, my panel with 2.7.2 is now in an endless reboot loop (with video footage to prove it). It loads the software “100%” and gets the flickering Qolsys screen for many minutes while the LED is blinking on green/off every second or so…and then after a many minutes the LED goes solid red, and the sequence starts over. I watched it go through this cycle 3 times, have a video recording of 2 of them.
My hunch is that the system lost time and that some verification check (a signing key?) fails due to invalid time…and since my unit hasn’t used the cellular modem in many months it can’t get time from that, and the WiFi connection to use NTP would come much later in the sequence.