The generally accepted final firmware for the IAP-205 is 6.5.4.18 .
If the AP is bricked or lost its image, you may need a from Aruba support. Place it on a TFTP server and boot the AP with a console cable. aruba 205 firmware download
If your access points are standalone or managed via a "Virtual Controller" (without a physical hardware controller), you need the firmware. The generally accepted final firmware for the IAP-205 is 6