A paddle boat can move at a speed of 8 km/h in still water. The boat is paddled 12 km downstream in a river in the same time it takes to go 6 km upstream. What is the speed of the river?

The warning buzzer is temperature activated and could just be a bi-metallic strip that has got old and tired and wont bend back again to break the contact now that it is cooler . Or it could be a push-button type that needs to be reset into the " Green " position . That might be hidden away .
The warning is there for a reason and worked in your case because you checked to find the problem and rectified the blockage , so be very happy , you saved on a wrecked , seized motor !
If you cant find and fix it , then get a marine engineer to call ( problems like this is why they were invented ) and do it for you AND show you how to do it for next time .
And handwrite those instructions out with a sketch of the bits , and staple them into the back of your engine handbook , because you are a human and will forget .

Oh and you HAVE checked your Oil Level is good still ? and that it looks and feels good between your fingers , nice and sticky and oily looking , not thin , burnt black and gritty feeling ?