2 Motion Detectors That Went Offline After Changing Batteries

Have 7 motion detectors. Changed batteries for all recently. 5 of them were successfully reintegrated into the system. 2 went offline. I have tried **all** published troubleshooting steps, including multiple times using the pin hole, removing the batteries, leaving the batteries in, etc. No luck. Can we just trade in these 2 non-working sensors for some that work? This is taking way too much time to troubleshoot---particularly as it relates to merely changing the batteries. Overall, I like this system, but lordy, if thsi is what I will go through every time I change batteries---not good.Thank you.