I was tweaking my DHCP config file today, and I probably made a typo. I've done this before, and when the router (Linksys WRT3200ACM running OpenWrt 19.07.7) next reboots, various parts (primarily dnsmasq, I imagine) don't work, but I can usually log in via SSH and fix it with no problem.
Today however, I was not able to reconnect to the router. I tried powering off and on a few times, and then I noticed the router's address had changed to 10.126.95.82. When I went there, I was greeted by the stock Linksys web interface login page. Somehow the router was now running the stock firmware, without me doing anything more than power cycling a few times (and possibly crashing dnsmasq with my bad typing).
Has anyone else experienced this before? I had thought that when I flashed the router to OpenWrt, the old firmware was gone from the machine. Does Linksys have some kind of backup anti-bricking system that re-installs the original firmware automatically? I'm so curious!