OBDII port not working

Hello all,

I recently changed the radio head unit in my car, far from the first time I have ever done that, with the battery disconnected. Then when I reinstalled the radio and plugged the battery back in the electric door locks stopped working, the D in the shift indicator blinks, the check engine light came on, and the OBDII port does not work. I have checked all the fuses under the dash and they are all fine. The car still starts up and runs like normal.

Being unfamiliar with Hondas, any help would be much appreciated. Thank you!

-Ryan