All LED lights blinking intermittent and not able to log in

Sorry, should have clarified, I used both addresses, the mywifi when trying to set up the extender and the routerlogin when I was trying to see if something was wrong with my router.  Neither would work, the mywifi worked once randomly, long enough that I thought I set up the extender but now not sure all all the lights keep going thru this routine and don't stop.  

What installation assistant?  I didn't have anything like that pop up - I refreshed over and over when trying to set up the extender and as I said it randomly popped up finally...there was no assistant, I just clicked on set up new extender, had to check both 2.4 and 5 and put in the password I wanted.  How do I find the installation assistant?  That would probably help!  I will reset tonight and try again and also try your hint of moving slowly towards where I want it to go.   Have an open concept house so not sure what could be disturbing it, the router and extender can just about "see" each other.  :)