IBS-TH2 Plus Bluetooth not working

Yesterday, the batteries died on one of my IBS-TH2 Plus sensors. I changed the batteries and since then the device is not being found by my IBS-M1 gateway, nor is this particular sensor being detected by a BLE scanner; other Inkbird devices are being found by the BLE scanner.

Yes; the BlueTooth symbol IS displayed on the screen of the TH2, and I am able to toggle it via touching the button on the side of the TH2. The power bar displayed besides the temperature is full.

Please remove the battery and wait half an hour before installing it, will it connect to the IBS-M1?
If not, please connect IBS-TH2 PLUS directly to the Engbird app via Bluetooth, will it connect? This will help us to check if it is a Bluetooth problem.

Problem tracked down and solved. Seems I had confused myself over which device was which. I had a list of device locations and Bluetooth MAC addresses and had mixed up some of the mappings.

I have same problem where one of my IBS-TH2 lost connection. I have replaced the batteries after removing the one in for 30 min as detailed in your explanations. I still cannot find the sensor through the Engbird app. It really feels like the bluetooth is broken. What should I be doing since this sensor is less than a yer old?

Maybe you can use the INKBIRD app? The INKBIRD app now supports the Engbird app products, please select the IBS-THS model for pairing, does it work?