Images supplied by Zebra are for their internal firmware flashing utility and I doubt if it would be possible to flash them in using low level "BIOS" utilities.
The most likely problem with this device is flash memory corruption. Try booting it's secondary FW. If it fails as well register RMA and send this device for replacement - it should still have a "limited lifetime warranty".
No wonder that your AP-6532 fleet went to less than half in number as (according to my personal observation) these series had poor flash hardware that overtime wore off and rendered these APs inoperable. Newer models had far less issues with flash m...
