DIAGNOSIS That's the machine's way of telling you it's hit a self-protection mode, almost always because it thinks there's a water supply issue or the side tank is empty.
FIX First, check the side tank. Make sure it's seated all the way down on the base—it can feel clicked in but not be. Pull it off and set it back firmly. Fill it with fresh, cold water if it's low. If the tank is fine, check the water line connection to the back of the machine. Make sure it's not kinked and the quick-connect fitting is fully pushed in until it clicks.
IF THAT DIDN'T WORK The flashing red and blue can also mean the machine is too hot. Unplug it and let it sit for a full hour to cool down completely. While it's off, check that there's at least a few inches of clearance on all sides, especially the back, for air to move.
HEADS UP Don't just keep resetting it without checking the water. The pump can get damaged if it's trying to run dry. If the lights keep flashing after you've checked everything, the thermal fuse might have popped, which is a known failure point and requires a service call.