PROJECT:DCMS_DEMO:prj1
BLOCK:de_top:blk1
BLOCK:new_block2:blk2
BLOCK:test:blk3
CHECKLIST:Block_DV:checklist1
CHECKLIST:Block_Physical_design_checklist:checklist2
CHECKLIST:CAD_checklist:checklist3
CHECKLIST:DFT:checklist4
CHECKLIST:Formality_DCT_Vs_ICC:checklist5
CHECKLIST:Formality_RTL_Vs_DCT:checklist6
CHECKLIST:FrontEnd_Design_Checklist:checklist7
CHECKLIST:Fullchip_Physical_design_checklist:checklist8
CHECKLIST:ICC_DPMHV_Checklist:checklist9
CHECKLIST:ICC_L2_Checklist:checklist10
CHECKLIST:ICC_Top_level_Checklist:checklist11
CHECKLIST:Overall_DV:checklist12
CHECKLIST:Power_analysis_checklist:checklist13
CHECKLIST:Synthesis_L2_checklist:checklist14
CHECKLIST:Timing_analysis_checklist:checklist15
CHECKLIST:checklist_tmp:checklist17
CHECKLIST:synthesis:checklist16
CHECKLIST:test:checklist18
CHECKLIST:test_copy_checklist:checklist19
[download]

And where is your problem?

Is your problem in reading the list file? Is your problem in renaming the files to the wrong names? Is your problem in not renaming the files at all?´

If you run this SSCCE then you see where one problem is

#!perl
use strict;
my $map = {
  one  =>1, two  =>2, three=>3,
};

my ($regex) = map {qr /\b(?:$_)\b/ } join '|', map {quotemeta} keys %$
+map;
change_file('test.txt',$map,$regex);

sub change_file {
    my ( $fn, $map, $regex ) = @_;
   # print $fn;

    open ( my $fh, '<', $fn ) or die "Could not open file '$fn': $!";
    my $str = do { local $/; <$fh> };
    print $str;
    close $fh;
    my $num_replacements = $str =~ s/($regex)/$map->{$1}/ge;

    if ( $num_replacements ) {
        write_new_file( $fn, \$str );
    }
}

sub write_new_file {
    my ( $fn, $str ) = @_;

    open ( my $fh, '>', $fn ) or die "Could not open file '$fn': $!";
    print $fh $str; #<-- error here should be $$str
    close $fh;
}
<
#test.txt
__DATA__
one two
three four 
five
[download]

poj

What do you mean by "renaming the contents of the files"?

A file has a name and has content. The rename system call changes the name, not the content.

If you want to change the content, you will need to rewrite the file using open and print.

Please go back to step one and describe in short, simple English sentences what you have, and what you want, and what steps you think you need to take to get from the one place to the other.

I think you're confusing rename with rewrite.