Originally, I was trying 9.8.1 on 206.x, if I had tried 110.x it might have succeeded. As I found out later that the flash chip on the AP was a newer version and wasn't supported by the 9.8.1 firmware.
I was able to upgrade the firmware on a T300 AP that was running 206.x. But first I had to downgrade to 204.x. Then followed the instructions in KBA-5193.
