Microwave displays H0 or HO and will not start; often associated with child lock or demo mode.

User-level fix:

• Consult your Farberware manual for the exact child lock procedure. Commonly, press and hold the STOP/CLEAR or 0 key for 3–5 seconds until the lock indicator disappears.
• For demo mode, some models require pressing and holding STOP/CLEAR and START together for several seconds, or a specific key sequence listed in the manual.
• After disabling, test with a short 30-second cook cycle.

If the display continues to show H0 and will not respond to the unlock sequence, the control board or keypad may be faulty and require replacement.