The short answer
When a Black+Decker microwave does this, a pattern of dead buttons names the part before anything is opened. Testing every button is free and takes a minute; a worn keypad on a countertop oven usually decides the replacement question.
What you actually see
- One or two buttons no longer respond — Isolated dead buttons are a membrane fault rather than the logic behind it.
- The clock resets whenever the oven runs — A control losing time under load is a supply symptom.
- Settings will not stick — A control that forgets is being interrupted rather than failing.
- The oven ignores the power level setting — A machine that accepts a level and ignores it separates the input side from the load side.
Causes, ranked for this microwave
- Membrane keypad worn or damp — Leads the ranking — a pattern of dead buttons grouped together is a broken track; scattered failures point further back. Where this checks out clean, treat the next entry as the working theory rather than a possibility.
- Child lock or demo mode engaged — Close behind — a lock is entered by holding a button and a demo mode by a button combination, and both are triggered while cleaning a panel. A clean result here does not just remove one part; it removes everything that depends on it.
- Steam or grease behind the panel — A step down — it is why a panel fault on a heavily used kitchen oven often appears and disappears with the room humidity. It is worth being sure about this one rather than half-sure, since everything after it assumes a verdict.
What to check, in order
- First — the keypad — Press every button and note which respond. Adjacent dead buttons are a track; a single dead button is a worn contact.
- Second — the lock and mode indicators — Look for a padlock, a letter or a symbol shown alone on the display. Any of those is a mode rather than a fault.
Checks an owner can do safely
- Step 1. Write down the exact code — Note the characters shown, whether the oven still heats, and what it was doing when the code appeared.
Tools: pen and paperAbout 5 min
- Step 2. Power-cycle the oven properly — Unplug it for several minutes until the display is completely dark, then restore power. A quick pull and push does not clear a stored state.
Tools: noneAbout 10 min
- Step 3. Look for a lock or a demo mode — Hold each button for several seconds in turn and watch for a lock symbol appearing or clearing.
Tools: noneAbout 10 min
Before you open anything
Safety
Unplug the oven before anything else. A microwave stores enough energy in its high-voltage capacitor to be dangerous with the cord in your hand. Do not remove the cabinet, do not hold a door switch closed, and do not run the oven with the door damaged or ajar.
When this becomes a service call
Stop and call when the next thing to do meets any of these. Call, or replace the oven, when a proper power cycle changes nothing, no mode is set and the keypad responds normally.
Sources
General guidance- The Control of Hazardous Energy (Lockout/Tagout) — OSHA 1910.147 and manufacturer service manuals, fetched
Nearest pages
What this page does not cover
Read this as generalized information. It is accurate across the Black+Decker microwave range, which is exactly why it stops short of the detail a single family or model deserves. If a family-level or model-level page exists for your unit, that page supersedes this one on wiring, part numbers and error-code meanings; the links under Related pages are where those pages live.
Lead Appliance Repair Technician · 12 years experience
Experienced technician with 12 years specializing in washing machine and dryer repairs across all major brands.
