I am having the same problem. I just want to calibrate my phantom. I have read that dji was having trouble with the new Firmware update so they took it off the server. Anybody know how you can tell what Naza M your Phantom has? Because it looks like DJI phantom assist software is for the Ver 2 NAZA M, from the download page on the phantom as compared to the Naza m download page. Just compare the versions on the Naza M Ver 2 to the NAZA m. I have no Idea if it makes a difference.
From the NAZA M V2 download page: Naza-M v2 Assistant Software v2.16
From the NAZA M download page: Naza-M Assistant Software v2.14
From the Phantom Download page: Naza-M Assistant Software v2.16