It isn't over yet. Real Madrid's appeal has been denied and therefore Los Blancos are out of the Copa del Rey unless the CAD decides otherwise.
Real Madrid C. F. has received and analysed the resolution of the Appeals Committee, which once again verifies that the player Denis Cheryshev was not notified of his ban, the only way the aforementioned ban can take effect.
The club has therefore submitted an appeal to the Administrative Court for Sport.
It doesn't seem very likely that the CAD will make a favorable decision for Real Madrid given the history of this court, but Real Madrid definitely must try to see if they can keep fighting for the title.
Remember that Cheryshev was suspended and therefore couldn't play against Cádiz, but he started the match and scored Real's opening goal because of a mistake. Real says that neither the player nor the team were aware of Cheryshev's suspension, so the suspension could not be effective. The CAD should make a decision soon if Real want to play the return leg.