I just performed this repair on my late 2018 mac air. I did click the gold button but saw no LED illuminated or otherwise. Question- after reassembly does the button get pressed again to connect the battery? Please clarify if this button is to be pressed and if it needs pressing again after the repair.
All said - I pressed again after the battery connector clicked, assembled the back and all worked perfectly. The original issue was one dead port (no charge, no communication). The battery charge lightening bold icon was acting funny too. Genuis bar guy in Naperville said it was likely a logic board too. But it was not. The port was apparently confusing the logic board with regards to the charge function. Thanks Adam for saving me $440 and sending my computer back to Apple. I am 71 yrs young - who says an old dog can’t learn new tricks with good training!!