I have AC800M PM861A controller new, the fault LED is flashing.
What is the status of Run LED ? Did you completed successufly firmware upgrade ver. 5.0?
Please look in the help from Serial Firmware Upgrade tool:
R(un) led=switched off
Flashing of F led generally means there is some problem with the firmware = it is not properly loaded, or may be the CPU has internal fault (need to send back to ABB).
For me ver. 5.0 seems a little bit old - it is better to try with 5.1 first.
I faced the same problem, trying to load the older version 3.2/16 of the firmware, in order to connect the CPU to existing old system. Process has been terminated when the tool tried to erase flash (second stage).
So first I made successful upgrade of the firware to ver. 5.1, then set the IP, then manually load the older version - using of File -> Load Bin File
The old firmware bin file you can find in your CBM 5.0 directories.