AT transmission issue after oil pan replacement
 

I recently replaced my son's oil pan and right-side control arm on his 2006 Mazda 3 2.3L automatic after he hit the curb hard. It wasn't a fun job but was able to squeeze the pan in and replace the control arm.

However, after refilling with new oil it doesn't seem to leak (not yet anyway) but now when I put it in gear it doesn't engage the transmission. It feels like it goes into gear (slight jerk as before) but the car doesn't move forwards or backwards and the ABS check engine line is now on (it wasn't before I started this job).

Can I have installed the oil pan or the control arm incorrectly somehow that's causing this? The car hasn't had any transmission issue even after the incident before I worked on it so something must have happened while I was replacing the oil pan and/or the control arm but not sure what. Any suggestions? TIA.