The message "Brewer err" occurs when the main board of the machine fails to communicate with either the board handling the steamer or the board in the actual brew group.
If connections for the brew group have polluted, this can also result in an error.
Normal handling of the system does not comprimize this system, but if the contacts are exposed to either water or coffee ground, the can get dirty / correded. Following the proper procedure when removin the brew group: First open dor, bottom piston will rise. Then press CLEAN and bottom piston will go down again and brew valve will open, releasing the water pressure on the connectors. Then switch main power off and remove the brew group.
When inserting a new group, make sure it is all the way in and tighten the holding screw firmly.