The problem with bench testing motors is that it only has one bearing on the brush/comm end supporting the armature. The coupler end needs the support of the input shaft.
A quick search of the archives brings up the following. It is a different error code based around the Field Fets on a T3 controller, but it gives you an idea what you will be dealing with.
Since yours is a T6 the internals may be different so be flexible that it may not look like the pics in the threads. I can’t seem to find anything ref a T6 and a few others I have asked have suggested that since your label looks to be a remanufactured label from FSIP that it may be a typo or some custom config since you are in the UK?. You could try contacting them directly to see if they have any info in their records.
Post some pics when you get it open.
Best to identify the FET part numbers from what you find inside.