my $logFile = "/icd/rc/genus22/logs/genus_221/v22.10-d037/lnx86_64_opt/1/tamper.log"; 

open (my $fh, '<', $logFile) or reportErr($!);
 
if ( grep{": FAIL"}<$fh>)  #FAIL found anywhere in file!
{
    do something...
    exit or return...
}

# text "Fail" not found if here
do whatever...

sub reportErr
{
   my $error_text = shift;
   do something...
}