Check the ball valve on the thru-hull where the water is sucked in. If some how it got closed you will overheat quickly.

The water inlet is the lowest point in the system and the hose would have to push past the v-drive and transmission before water would be in the raw water pump. Follow your lines from thru hull up to pump.

A clog will cause this also. Most likely the heat exchanger. Remember if you are clogged upstream you cannot push the air out of the system to get fresh water in. 235 is scary but if that is all you got to, you should have avoided damage.