Express Console defaults to 24/48 after being deep cleared
When an Express console of any size is deep-cleared [power cycle the console while holding keys 7/8/9], it will boot up and think that it is an Express 24/48. This is due to the DIP switches for hardware type not being read at this startup.
In this state, the faders may be inoperable, or may be mapped in a strange way (since it will be attempting to use the faders as though they were an Express 24/48).
In order to get the console back into its correct mode, power cycle it once more without holding any keys. When it boots this time, you should see the correct version listed in the bottom right corner of your monitor in Setup.