One of my smart (Zigbee) LED bulbs started flickering, then gradually lost brightness over several weeks, and finally went completely dark.
It was an OSRAM SMART+ AC03641 2700k 810lm 8.5 Watt
I bought a new one (actually, I bought two new LED bulbs because this type is no longer available and because I need identical bulbs for my light fixture) and replaced it. Out of curiosity, I removed the frosted, transparent, hemispherical diffuser, which was destroyed in the process. But shortly after, I saw the problem with my magnifying glass: one of the two solder joints connecting the control board to the LED board had a hairline crack, see photo.
I resoldered the joint, and voilà – the bulb works again. Perhaps this is a common problem with this type of bulb? Next time, I’ll be careful not to damage the diffuser when the next bulb breaks. Unfortunately, the diffuser is glued in, but perhaps it would be possible to drill a small hole in it, just enough room for a soldering iron to repair the joint? And then seal the hole with tape (or maybe leave it open)?