Well, that's expected :-) to paraphrase your code:

sub somesub {
 # ...
 # ...

 # loop until $ecount is false
 # it is actually undocumented what this means
 # fetchrow_array is supposed to be called in list
 # context like so
 #
 #      ($ecount) = $sth->fetchrow_array();
 #
  
 while ( $ecount = $sth->fetchrow_array() ) { 
   # ..
 }
 # $ecount is undef here, probably (see above)

 return $ecount;
}
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the return statement is working perfectly, but your variable s will always be false (certainly not some "count").