There is a bug in https://github.com/NoahY/q2a-poll/blob/master/qa-poll-layer.php
Line 298
$answers[$idx]['vote'] = '<div class="qa-poll-voted-button" title="'.qa_html(qa_lang('polls/voted_button')).'" onclick="pollVote('.$qid.',\''.$uid.'\',\''.$answer['id'].',1)"></div>';
in:
pollVote('.$qid.',\''.$uid.'\',\''.$answer['id'].',1)
Before answer there is an extra \' that makes poll not work when a user want to cancel his/her vote.