This basically means that the player is unable to create or recall the RSA key it generated to communicate with XMR (push messaging from the CMS).
Rekey only clears the key from the CMS side, allowing the Player to send a new key. As this doesn’t work it is possible you have a corrupted key in stored in the player that isn’t being cleared.
Can you try deleting all data for the application (which will require you to reconfigure it when you start it back up), so see if that clears the error.
I will record a 
for the next release to try and detect a corrupt key and self-clear it.
As a side note this probably isn’t great for the device