OMC 5.7

[Creakyrock08847]

So I recently purchased a 1987 bayliner 2550 sunbridge with a OMC 5.7 and I was told it ran great ( I was shown videos of it running last summer) it just needed the impeller changed so I changed the impeller and went to start it and it wasn't wanting to turn over but finally with some help ( pouring a little gas in the carburetor) it turned over but it then blew both exhaust boots then causing water to begin to pour in so immediately turned off the engine pumped the water out and started the engine up again ( it started immediately and sounded great) just to inspect where the water was coming in from. I then replaced both blown exhaust boots and now it's not wanting to start up my main question here is what would cause both exhaust boots to just blow like that is there something clogged up? I don't wanna just try starting it up again and blow them again or even break something eles. This is my first boat and just first form post ever in my life so all of this is new to me so any help would be much appreciated thank you.
( the attached photo is what I'm referring to when I say exhaust boots because I'm not 100% if that's the correct name)

 

[alldodge]

Correct me if I misunderstood
It runs fine with the boots off, but if boots are installed it blows them off

If that is correct, pull the drive and look in the exhaust outlet on the transom. Something may have built a nest

 

[jerryjerry05]

Found a mouse's nest in a drive and a huge wasps nest in another.