If there is an exclamation mark blinking on the Grants microwave oven, this usually indicates that the microwave is malfunctioning. In this case, it is recommended that you check if the power cord is properly connected, check if there are any foreign objects inside the microwave oven, check if there are any damaged parts in the microwave oven, or check if the microwave oven has a damaged circuit board. If none of the above checks reveals any problem, it is recommended that you contact your local Grants service center for further assistance.