Similar error while attempting to update the Airport Extreme (model A1521) firmware to version 7.7.7. After clicking "update" for the APE in AirPort Utility app on my MBP, it looked like it was downloading and then restarting, but then the "error occurred while updating the firmware" message popped up.
It then disappeared from the AirPort Utility app. Checking out the physical APE, it's got a fast flashing amber light on.
Perform a "soft" reset per directions on apple support. No change in status in AirPort Utility or LED.
Perform a "hard" reset. No change.
Perform a "factory" reset. Solid green LED for 1 second, off for 1 second, then solid amber LED for 5-10 seconds, then flashing amber LED forever.
Removed all connections to APE, repeated above steps with identical outcome.
Attempted to connect ethernet cable to all ports, one at a time, to MBP and then into a port in another router. No connection.
Removed rubber base from bottom of APE to inspect physical reset button connection with ohmmeter. Button contacts are open when not depressed, shorted when depressed.
APE does not show up at all in AirPort Utility (not in "Other WiFi devices" either).
Pushing reset button on APE does nothing, no matter how long or when it is pushed.
Once power cord is removed and inserted, the indications are always the same, regardless of what I do with the reset button. Solid green LED for 1 second, off for 1 second, solid amber for 5-10 seconds, then flashing amber forever.
The ONLY interaction with the device, which had up until this point was working flawlessly for years, was through the software AirPort Utility. The only physical interaction came after the firmware update bricked it. I simply do not understand how a botched firmware update could brick the APE. The default firmware should still be able to be loaded with the reset sequence.
Please help.
