Nothing about the magnet ring hitting the sensor should have affected the DCDS board, so it it was good before, it's still good.
When you put the magnet ring on, it is essential that it be true, and that it can not contact the sensor. Truthfully, it probably didn't kill the sensor if it's still intact, just rubbing on the plastic case won't damage it. It's a hall effect sensor inside, fairly robust if you don't break the plastic case.
I pull the wheel, glue the magnet ring on and make sure it's totally dry and true, then press the flywheel back on. The only other thing is as I mentioned, the end play of the armature has to be considered when spacing the flywheel. I have it about 1/16" at it's closest, and unless the motor is damaged, the end play should not be excessive.
