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Hello @0805MJM, have a warm welcome to the Community, it's great to see new faces around. 
It's possible that the battery on your tracker is not making contact correctly with the metal pieces inside your Zip. Sometimes the side spring may be bent as a result of improper battery insertion or pressure being applied to the back housing.
Please verify that there is proper contact between the battery and the battery contacts inside your Zip tracker. You can do this by opening the battery door of your Zip, removing your battery, and ensuring that the silver battery tab located in the lower right half of your tracker is flush with the white box outline in the tracker housing. Check this image explaining the process.
In case this doesn't do the trick, my best recommendation would be contacting our Support Team. Let them know about everything you've tried so far, I'm sure they will be happy to assist you further.
Give it a try and in case you need anything else, feel free to reply! 
Best Answer