It is always best to indicate what year of a SHO you have.
The first thing is to try and get the electric motor running again, either by looking at your dash switch or the signal wire from your head unit (depending on what year you have.)
If you can't get the motor running, the unit has to come out, which is no picnic.
I have found it is difficult to get the correct mast with the correct barrel adaptor, so take a long look at what you bought.
The easy way to change masts is to pull the old mast toothed white plastic strip up and out. then you have to contend with getting the metal end out which usually involves a lot of penetrating oil and lots of luck. Remember which way the teeth are pointing, but I am sure your instruction sheet has that information.
The theory is if you can get the motor running and you have all the old mast out (you have to compare the length of toothed plastic rod you have bought with the 2 pieces of the broken rod), that you can wind the new rod back in using the motor.
I have never got that to work as the first untoothed end of the plastic gets caught at the first bend in the winding drum.
I took the winding drum apart which was full of surprises, so take pictures at every step of disassembly.
I found that most universal replacement mast assemblies were exactly like the SHO original unit, except for the complicated fender attachment which is more or less on the side to the fender. To make it fit well, you have to swap out the metal tube part that goes from the drum to the fender part.
There are lots of write - ups on this forum that show you how easy it is to change masts, problem is, I never got any of the directions to work out.
Good luck.