Flywheel is locked up please help

[Lightning2015]

I just installed a new lower unit during the weekend took it out on Sunday and I was trolling some lures and my 1998 200xl hp Mercury just suddenly stopped and the flywheel is stuck so I had to get towed in when I came home I took the lower unit off that I just installed and flywheel is still locked up i had the power head rebuild in 2013 what could be wrong I'm all bummed out

 

[Faztbullet]

Pull the heads and inspect...

 

[enginepower]

Sounds like that thing is lean or not getting oil. When you had it rebuilt, did you find and fix the cause of why it failed? Otherwise, it's just going to keep happening.