ABS unit bad; cannot access the rear of the ABS unit plug

You need to remove the HCU and brake module as a unit and then you will have access to the plug so that it releases.

Here is a guide as well that will help with this:

https://www.2carpros.com/articles/how-to-replace-a-abs-controller

Here are the instructions below for more detail on this. Let me know if you have questions on this. Thanks