Only post a SSCCE. The problem is that OLE::Win32 will not save to a path with forward slashes so you need to convert / to \\ as I showed here.

#!perl
use strict;
use warnings;
use Win32::OLE;
use Cwd;
$Win32::OLE::Warn = 3;      

# get already active Excel application or open new
my $Excel = Win32::OLE->GetActiveObject('Excel.Application')
|| Win32::OLE->new('Excel.Application', 'Quit');  

my $dir = getcwd();

my $excelfile = 'Parameters.xlsx';
my $Book = $Excel->Workbooks->Open($dir."\\".$excelfile)
  or die Win32::OLE->LastError(); 
  
# do work

$dir =~ s!/!\\!g;
$Book->SaveAs($dir."\\".'updated_'.$excelfile);   
$Book->Close;
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