Yes I had this happen and eventually gave up going round in circles trying to get it started, and contacted Abbot, who "interrogated" me (they'll also ask for both your reader and the sensor serial numbers), and sent a replacement sensor together with packaging, etc, for returning the duff one for analysis.
You can use the little cog symbol on the top
RHS of your reader screen to access the Setting menu, and under System Status you'll find the Event Log which will give details of the fault: date, times and error codes for the failure, which I also quoted to them.
Robbity