Maybe not worth the wait.  Don't sweat it as nobody responded to my homing issue.
But as a fellow user who has little to do in pandemic induced social isolation, maybe I can help.

First I don't think its possible to re-direct the Z limit to the probe.  That probably would mean changes to the firmware that are unlikely to occur just to satisfy your situation

Now, I'm going to assume that you have actually double checked that the probe switch is going to ground at the terminal block on the unit.  ..and that you have measured this with a DMM or a scope.  

It is pretty hard to destroy the inputs on the DCS because they are optically coupled.  So I would not assume that you blew the probe input.
More likely you are doing something wrong in the probe operation OR there is some Settings issue OR  firmware bug.

Here is what I would try.  Upgrade to the latest firmware up on the Facebook page. Link

It is called install(2020-03-06-112)-zip   Be advised you may have to go through and re-setup your settings.
But I think it is always wise to get the latest and greatest software.  It seems to me that the DCS firmware is still in a rapidly evolving stage.

Now if you could provide us with some detail as to how you are testing to establish in your mind that something is wrong with the probe input?Also what are you using probing for?

Sorry, but is it worth the wait?