I agree with Peteyb, or it could be a too hot warning but if it does it just after starting and engine is cold thats where I would start first or maybe you could have faulty ignition.
I had the same problem with my Mercury. I replaced the alarm module and found that wasn’t my problem. It turned out to be the sending unit from the oil tank. It went bad and the alarm sounded continuously. It was an easy fix.
I blew up a motor after I checked everything out and thought it was OK. I checked the water pressure gauge and the water stream, checked the oil level and made sure the primer bulb was tight on my oil reservior. I had a clogged vent on my oil reservoir cap. When air cannot get into the reservior oil cannot get out. No oil mixed with gas = blown motor.