If you have experienced the key not working, it could be for 2 reasons;
- FarSight / Steam are updating their server software
- there is a mismatch in files/updates
With #1, please check the game software the next day as generally, the software updates have occurred over the weekend and should be solved within 12-24 hours.
If however it seems cabinet mode is still not working and you believe reason #2 is the problem, please follow these steps;
– go to C:\Users(ComputerName)\My Games\Pinball Arcade
– look for and delete the Arcoodainfo.dat file
– then restart steam, activate pinball arcade, and re-enter the key