PSA: GRILLPLATS smart plug firmware update reboots the plug - don't power your HA miniPC from one and check your CMOS battery

IKEA Matter plugs reboot when they install an OTA firmware update. The relay drops. Whatever is plugged in loses mains power. The plug comes back ON, but if your PC's BIOS is set to "stay off after power loss", it stays off. I had Home Assistant itself plugged into one. HA updated the plug, the plug killed HA, and HA was the only thing that could turn the plug back on. This was a remote instance of HA - two hour return trip.

In my case the BIOS setting wasn't even the problem, I had it set to power on after AC loss. The CMOS battery had died, so the BIOS silently reverted to defaults, and the default is "stay off". Check your coin cell.