The Schneider 5AP920.1505‑K44 is a 15‑inch, single‑touch resistive HMI panel from B&R’s 5AP series, featuring a 1024×768 XGA TFT LCD with 16.7 M colors and an LED backlight, powered by 24 VDC and protected to IP65/NEMA 4X. Common failure points for this class of panels include power‑supply voltage drops or spikes, touch‑digitizer wear (especially on the glass), display driver board faults, and connector corrosion or loose USB/serial links. First‑check diagnostics should verify a stable 24 VDC supply to the panel, inspect all cable connections for tightness and signs of damage, and review any error codes displayed on the HMI or logged in the connected PLC; if no fault code appears, perform a visual inspection of the touch surface for cracks or contamination that could impair input.[oss-gpt-20b]