The built-in HDMI inputs have individual status lights. This is a list of the possible status conditions.
LED OFF - No Signal
LED GREEN - Valid Signal and HDCP 2.x
LED GREEN (Flashing - 5 second ON / 0.5 seconds OFF) - Valid Signal and HDCP 1.4
LED ORANGE - Valid Signal without HDCP
LED RED Flashing (1 second ON-OFF) HDCP Problem
LED RED - Unrecognised resolution (INVALID)