A:Answer Hi SantaElg- The colon ( : ) will blink / flash when programming a new time of day. To program the clock, press Clock. Enter time of day. Press Clock to set the time. Also, to confirm power, the unit has an interior light that comes on when the door is opened and when it is cooking. Here is the link to the Owner's Manual for instructions on using your microwave: https://products.geappliances.com/MarketingObjectRetrieval/Dispatcher?RequestType=PDF&Name=49-40735.pdf - Thanks for choosing GE! Keep in touch- Sue