Hard luck Kefi....
My electrical knowledge aint that good I'm afraid but I would look towards the starter solenoid mounted on the right hand side near the battery box (if yours is the same as my 93 900ss).
The haynes manual details how to test it.
I'd of thought this unit plus the fuse would of stopped too much damage but you might be as well checking your charging system voltage (when you get everything running again - lets be positive (oops - sorry)).
You wouldnt want to melt a battery like I did recently
Good luck - Frank