Wireless temperature sensors dying one after another

Symptom: Wireless sensor loses connectivity with hub. Reset and re-enable, but when pressing 4 times to re-enable, the sensor responds with 4 blinks instead of one and never connects. I now have 3 sensors in this state and one which is completely dead (no LED blinks at all). What should I do?

I have tried all that, I now have 2 dead sensors and 2 that blink 4 times after reset. I would be WONDERFUL if I could actually get technical support with these without having an expensive contract. I've purchased about 10 of these now, and all have died in the same manner.

What is the distance between the sensor and the wireless hub - in direct line of sight (so no obstacles) ?

I am having the exact same issues as OLESENSOR I have done everything but the wireless sensors just dont stay connected.
I had to purchase 15 of these and all but two have died off. The two still connected are the farthest from the wireless hub.
even if i bring the sensors right next to the gateway hub they will not connect or will not stay connected.

Any help would be grateful

The farthest could be working since they are in a direct line of sight of the hub. Typically a hub would be ceiling mounted with antenna pointing downwards and sensors pointing upwards. Remember that a closed rack has the same effect as a Faraday cage. You could also mount a bigger antenna on the wireless hub to improve reception.

I have FINALLY found the issue: Batteries. The "battery level" indication is completely USELESS and does not indicate anything about the health of the battery. I too all 7 sensors apart and noticed that the circuit boards were slightly curved because the batteries were actually BULGING. Once I put in new CR2450 batteries ALL 7 sensors work just fine. The crazy thing is that the company puts a big "void if opened" sticker on the sensors as if you are supposed to just purchase a NEW $50 device when the battery runs out. As for updating to the latest firmware, I have tried that too, but any version after 5.11 causes the gateway to become unreachable through a port-mapping gateway when the security (login) time expires. Everything works fine in 5.11.

we are glad your issue is resolved, in regards the warranty sticker, it is OK to remove it on wireless sensors as you have to to replace batteries. this will not void your warranty.