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Hi People! My MacBook’s Wi-Fi and Bluetooth showed “No hardware installed” about a week before the macOS Mojave public release. I have seen this in the past too but mostly it was Bluetooth but this time both were showing same issue. It went away just by restarting the MacBook for 3-4 times.
Sounds like your I/O board cable is not making good contact or needs replacing. Review this IFIXIT guide MacBook Pro 13" Retina Display Mid 2014 I/O Board Replacement. Jump down to Step 17 to disconnect it from the I/O board and then disconnect the logic board side as well. Inspect the connectors (all 4) do you see any discoloring of the contacts or the solder joints? Carefully clean the contacts with 85% or better isopropyl alcohol using a cotton swab (Q-Tip) do be careful! As you don’t want the swab to snag the contact legs on both the cable and the board connectors. Don’t forget the solder joints as well. Here’s the I/O cable MacBook Pro 13" Retina (Late 2013-Early 2015) I/O Board Data Cable and if the I/O board is to badly damaged here’s that part MacBook Pro 13" Retina (Late 2013-Mid 2014) Right I/O Board
