The IMP will give a short green flash as soon as Blinkup finishes, but you have to be quick to see it. I think the quick green flash was made longer but you still need to be quick.
If you don't see the flash then try blinkup in a very dark environment, you're looking for that quick green flash as soon as blinkup finished.
Check wifi range at IMP location.
If Blinkup (quick green flash) has worked but still no wifi, then double and triple check the wifi credentials zeros and ohhs, ones and els, that kind of thing.
If the credentials are good, check the acess-point isn't operating on channels 12 or 13. The USA version of anything wifi including domestic IMPs aren't permitted to use these channels but outside of the USA about a third of all AP's are using channel 13.
Using the above steps has solved my blinkup troubles everytime, Hope it helps you.