Inside black box there are two connection points. J1 & J2. Usually these are connected with a jumper. If you remove this jumper the unit will not load above 90%. Please check this and if there is no jumper, install one if you know why it is removed.
In calibrated FLA you should receive approximately 8,25VDC in V1-V2. I usually calibrate the Capacity Control Module (CCM) to start current limit condition at 8,07VDC.
I’ll send you a useful service bulleting if you send me your email address, but I don’t believe that the black box is damaged. Maybe current calibrator needs to be readjusted.
If you have 8,25VDC at your 80% then current calibrator need to be recalibrated.