Sentex Systems MINIKEY1005 is a self‑contained access‑control keypad that drives up to two relays, supports variable code length, and stores credentials in non‑volatile memory with optional lightning protection. Common failure modes include loss of keypad response (often due to power supply dropout or internal capacitor degradation), relay lock‑up (typically from solder joint fatigue or overcurrent), and corrupted password storage (usually caused by voltage spikes). First‑check diagnostics: verify 12 V DC input and monitor for ripple; inspect the relay contacts and test coil resistance; perform a visual inspection of the board for cracked traces, burnt components, or swollen electrolytics.[oss-gpt-20b]