The Thermoblock is severely corroded or clogged with scale, preventing it from reaching the required temperature to brew coffee.
The Over-Temperature Protection is defective or blown. This fuse is a shut off mechanism when the Thermoblock exceeds the max temperature, or there is a power surge during the brew process. If this fuse is blown, it may indicate there is an underlying problem in the circuit.
Visually check the fuse and contact pins for corrosion. Also, check the OHMs reading to ensure there is a connection. It is recommended to replace the temperature sensor and fuse.
The Power Board is defective. The board is failing to receive the necessary signal that the coffee thermoblock has reached the required temperature to initiate the brew process.
Replace the PCB; however, it is more economical to buy a new or refurbished machine.