I am the proud owner of a new Pi3A+, and got it up and running no problem. However within a few days (probably 2 hours of power up time) the wifi connection started failing.
Eventually hooked up leads (KM and HDMI) and found that ifconfig shows no wifi entry.
Went back to NOOBS v3.0.0 and found that the wifi icon is grey'ed out.
After much testing, frustration and googling, not to mention umpteen failed attempts to become a member of this forum, I am at a complete loss as to the problem.
The only thing I can suspect is a hardware failure. This appears to be confirmed by using a SD card I have in a Pi3B.
When booting with this SD Card in a Pi3B and holding the shift key, I get the NOOBS screen with wifi icon active (you can select it).
When booting the Pi3A+ with the same card, holding the shift key takes you to the NOOBS screen, but the wifi icon is NOT selectable.
I've seen loads of posts about this and that, amend various files and run various commands, but my thinking is that booting to the NOOBS screen fundamentally preempts any of that.

Can anyone help?