Good that you found the reason for the problem. I think next time you will triple check everything.
Hope that the damage is not caused by the workshop who tried to bring the sensor closer to the DMF flywheel teeth. But it can also be a shipping problem. DMFs are very damageable.
Also please check again the current distance between the modified sensor and the DMF teeth. If the distance is too close this can cause problems, because the voltage generated by the sensor will be different. This can sometimes confuse the ECU.