After a hard reset, wait 2 minutes for the router to fully boot. The LED should be solid yellow/amber. Then try the sticker password. If it still fails, the sticker might be for a different unit, or the hardware is faulty.

As of mid-2022, Xiaomi pushed a mandatory change via firmware updates and new hardware revisions. The is as follows:

It was more than a router; it was the nervous system of his life.