DIAGNOSIS This is a classic power interruption fault. The most common cause is a failed power switch (the rocker switch on the front). The switch contacts wear out and cannot sustain the current needed for the heating element.
FIX Unplug the unit. Press and release the ON/OFF rocker switch firmly 20-30 times. This can sometimes clean oxidized contacts. Plug it back in and try to start a brew cycle. Listen for a faint click from the switch when you press it.
IF THAT DIDN'T WORK The main control board may be failing to send power to the heating element due to a bad relay or a cracked solder joint. Intermittent operation points to an electrical fault on the board or in the switch wiring harness.
HEADS UP Do not bypass the power switch. The unit has high-current components. A direct short can cause a fire hazard. If the switch is faulty, the entire front control panel assembly typically needs replacement.