APM 2.8 AC3.2.1 "waiting for first HIL_STATE message"

After flashing 3.2.1 to my APM 2.8 which had been working fine, but I wasn’t sure which version of the firmware it was running, I am now getting these messages and I cannot perform any of the calibration steps:

Reflashing AC 3.1.1 doesn’t seem to help. Any help would be appreciated.

Support for APM/AC 3.2.1 is down to running on fumes. Replace the Flight Controller.

i have the same issue with my apm 2.8…
even the board is old, mine was working as well before flashing 3.2.1 quad instead of hexa…
is there any direction to solve this?

EDIT: re-flashed 3.2.1 hexa fixed the problem > flashed 3.2.1 quad and its all working again.

I tried reflashing Hexa and Quad without any change. Ordered a PixHawk.