DIAGNOSIS The descaling procedure was likely interrupted or performed incorrectly, leaving the machine in a locked error state. A solid red light indicates a fault.
FIX You must perform a hard reset. Unplug the machine from the wall outlet. Wait for 2 full minutes. While unplugged, press and hold the Espresso and Lungo buttons together for 10 seconds. Plug the machine back in. The lights should perform a startup sequence. If the red light is gone, attempt the descaling procedure again, following the steps precisely without interruption.
IF THAT DIDN'T WORK If the solid red light returns immediately after plugging in, the thermal fuse or a sensor in the thermoblock may have failed during the descaling heat cycle. This requires professional service.
HEADS UP During descaling, do not turn the machine off with the button. Let it complete its entire automated cycle, including the two rinse phases, until it returns to standby mode.