The reset procedure can be difficult, but after 6-8 times through the on/off cycle with 3 seconds on then 3 seconds off it should dim down, then return to full brightness. It’s not really a true blink.
Another potential issue is if your parents have a smart meter from the power company. Apparently several brands/types of smart meters use the same protocol (zigbee) and can cause enough interference that the bulbs won’t connect to ST.