I post this for interest, and would not recomend anyone to ever remove the covers from any equipment and attempt repair.
I Purchased my Dlink 300av adaptors from ebay, all worked intialy but one started to switch off randomly, went thru normal reset pairing power on off, to no avail.
Using my old mobile phone battery replacement tools, T6 and spudger, i removed the T6 screw on the prongs side of the adaptor,and using spudger leavered off the lid statrting at the reset button.
When opened all looked ok, but i noticed a brown stain below the small black capacitor ...size, low esr 100uf25v. Capacitor sickness it was called back in the day, blown capacitor or gunk oozing out.
I stress again this is for interest only and repairs to electrical equipment should never be attempted.