Trouble With Ecolink Door/Window Sensor

Hey all,
So far I’ve added about 10 Ecolink Door/Window sensors. All but one with no issues.
For some reason, this one sensor will not enter inclusion mode. I’ve done as the manual directs with no success. I also tried excluding it with no success.

I’ve left the battery out of the sensor for a few hours, set my SmartTihngs Hub to inclusion mode, insert the battery and replace the cover. The red LED will flash for a few seconds and then turn off.

Any ideas?

@eli_siegel, I have quite a few of those sensors. I’ve had no problem getting them to include until very recently. The last purchase of three I bought off Amazon had one that would absolutely not include. No matter what I did it would not include, so I worked the return/exchange process with Amazon and got a replacement. That one included perfectly.

An order of 4 the week prior also had one that was extremely difficult to include. All my other 20+ Ecolinks I’ve ordered several weeks back all were fine. Sorry I couldn’t be of more help.