Azu has been restored.
The status after restoration is as follows.
Press and hold the reset button to perform a factory reset. I immediately performed another factory reset, reinstalled the firmware, and then unplugged the power for about an hour.
I don't know which one worked, but I couldn't recover with just one factory reset, so I'll post it here just in case.
Before both RRC1258s went bad, there was a phenomenon where it became difficult to connect to the network. I felt like if I turned off the power and then turned it back on, things would go back to normal, but I started noticing that once every three months, then once a month, and then once a week, the intervals at which I had to turn off the power became shorter. I have a personal experience with it.