I have had mine about 4 months - though I will never know when it was manufactured and distributed and resold to the eBay seller I use.
Power indictor is Green - sat search is slow flashing blue.
The easiest way to check is probly using your "ground station! the Cleanflight multiclones variety, LibrePilot or whatever you use - presuming it give information of the number of sats you are showing.
There is also the uBlox centre online - which you will need to access at some point.
Myself - I have two Revolution FC and the M8N - to be honest I got so pigged off forever messing with settings that change and software that does not really work well - I gave up!
I purchased the Nasa M Lite - which took all of ten minutes to set up. As long again to sort out a 2 3 way switches
and its up and flying…altitude hold is a dream.
1 Revolution FC A$65 fromBangood.
I got two hoping for one good one - I got 2 good ones!
1 M8N A$29.50 off eBay total: A$94.50 + hours of time sorting it all out.
Nasa M Lite cost me A$100.
I have also just had delivery of the Nasa M v2 It cost me A$198 off Foxtechfpv - and its brilliant… but it depends what you want to do when flying it!