QSC 8.3 CM554 - No Start hard to diagnostic

[J99]

Hello,

Still facing a no start condition (only few seconds then dies) on a QSC 8.3 CAPS CM554. Fault Code down to error 276 (High current detected on injection control valve stator return) and sometimes error 456. Pressures look all good during cranking (5000 to 6000 PSI in accumulator). Quite some things already done:
- New Fuel Filters (both inline one + water separator one)
- Cleaned Lift Pump, pressure in spec
- New CAPS Fuel Pressure Sensor
- New Transient Suppressor
- New Injection Control Valve Stator + ICV Repair Kit done
- Updated ECM to latest official Cummins calibration for the model (J91384.12)
- All Click Tests work fine (on ICV and on pumping valves)
- Removed air up to injectors lines plugs into cylinder head

And still error 276...doing the procedure again, it comes down to asking to replace again the transient suppressor (step 3C-1 added late in the procedure) even when test is OK, or later on, to replace the Injection Control Valve.

I strongly suspect no mechanical issue as when starting a few seconds, it seems to run well, and it was working the day before we stopped it...

I would like to bypass error 276 to check at least if it is electronic only or mechanical, but I don't find the CAGT Block Fault Code Parameter in Calterm for these old ECM. I don't know what else to think of here...

Any idea how to block codes on these ECM ? or better diagnostic ideas / what to try next ?

Thanks for your help