Machine will not heat, brew button does nothing, and display shows E01 shortly after power‑up.

Safety first: Unplug the machine and allow it to cool completely before opening any panels. Hot boilers and live mains voltage are present inside.

Step-by-step checks:

• Power cycle: Turn the machine off for 5 minutes, then back on. If E01 returns immediately, continue with hardware checks.
• Check for obvious damage: Remove the top/side cover (per Rancilio service manual). Look for burnt wires on the brew boiler heating element and the thermal fuse or high‑limit thermostat mounted on the boiler.
• Test the heating element: Disconnect the two element leads. Use a multimeter on ohms; a typical Rancilio brew boiler element should show a finite resistance (often 10–40 Ω depending on model). If it reads open (OL), the element is failed and must be replaced.
• Inspect thermal fuse / high‑limit: Locate the thermal fuse or manual‑reset thermostat on the brew boiler. Test for continuity. If open, replace the fuse/thermostat and investigate overheating causes (scale, low water, failed sensor).
• Check the NTC sensor: The brew boiler temperature probe (NTC) is usually threaded into the boiler. Inspect the connector for corrosion or loose fit. Measure resistance at room temperature and compare to Rancilio spec; if it reads open/short, replace the sensor.
• Control board relay: If the element and safety devices test good, the heater relay on the main control board may be defective. Inspect for burnt spots or cracked solder joints. Replacement of the control board is typically required.

When to stop: If you are not comfortable working around mains voltage or cannot access the boiler safely, stop and contact an authorized Rancilio technician.