Digging up an old thread, just in case somebody else happens to get this machine (fanless + shipped with SSD) for free like just I did.
I had to mess with b43 wifi for several days, facing all the "rfkill turned hardware button off" etc errors.
But, apparently this is a BIOS issue: a simple "Load Setup Defaults" in the BIOS got wifi working for me.
Inspiration:
https://bbs.archlinux.org/viewtopic.php?id=177742dmesg says
Direct firmware load ffor b43(/lp0bsinitvals15.fw failed with error -2;
Falling back to user helper;
ieee80211 phy0: Selected rate control algorithm 'minstrel_ht'
So there still seem to be issues loading the driver.
Still, now with BIOS ver A05 + kernel 4.14 + firmware-b43.tcz + wireless-KERNEL.tcz + wifi.sh + nothing blacklisted in extlinux.conf wifi finally works.
EDIT: The wireless switch (Fn + 2) doesn't seem to work in MicroCore, though.
[EDIT]: Added code tags. Rich