I just had a similar problem with mine after I did a factory reset in preparation for rooting it. After doing about a half a dozen factory resets, the problem went away. No idea why. What finally worked was doing a factory reset, then before doing anything else, immediately getting a wi-fi connection to my router. Then I was able to set up my Google acct, etc.
The symptom mine displayed was that it went through an endless loop of connecting and disconnecting with the router.
The other thing I noticed is that if it is in near vicinity of other strong wi-fi signals, it won't connect to my router. I was sitting at my desk, with my tablet and phone both at arms length. When I turned off the wi-fi on both of those, the DX100 connected faster and more reliably.
Hope this helps.