We just bought new LED bulbs to replace the old (non-LED) bulbs in our outdoor floodlights. Old bulb=120W; LED=15W. The LEDs are rated for use outside, and are Edison style. The problem is: when we turn the light switch on, the bulbs give a single, very fast (~300-500ms) "on" blink and then turn off. They never turn back on. Any thoughts on trouble shooting would be appreciated. Thanks.
They might be cheapo's. But most likely, there is a "smart or powered switch" somewhere in the works. Motion sensor, day/night sensor, who knows what?
Whatever it is, it's not playing well with the LED's.
The surest way to test this is to put 1 incandescent back. If it suddenly behaves properly now, then an obsolete electronic thing is at fault.
You can either modernize it (note many such things require neutral!), or make at least one bulb a "better" grade of LED which is designed to play nice with these types of obsolete devices. Often they are marketed as "dimmable".