some idiot put battery in backwards and messed up an otherwise healthy car i just purchased.. since then I have no power to ignition but everything else lights up..have narrowed it down to possibly an 80 amp fuse under the hood blown but when i went to get it out it seemed welded so undid bolt and removed what I could of it... problem is instructions to replace it say just pop it out and replace.... nothing about undoing bolts etc..... what have I done now???????????? any help or suggestions... as to what to do next....thanx in advance!! jj