Update Statement mySQL issues - php

Question

I am having trouble updating the posts table of my database when a user updates a blog post they have made.
Flow of events - user makes a blog post, its saved to DB then they can go back and edit it. Edit brings up a pre-filled html form populated with data from the posts table. Then the user can change the title and content and when they press update the posted values from the form should replace the title and content of the original post in posts DB all other columns remain unchanged.
Currently my database just doesn't seem to update, not sure why. Using a combination of html/php/sql/pdos to execute sql statements - getting very complex for my novice experience and any help is appreciated.
Code (UPDATE statement is at bottom and most problematic):
// begin edit post
if(isset($_GET['editPost'])) {
$editPostId = $_GET['editPost'];
$sqlEditPostCheck = <<<EOD
SELECT author, id FROM posts WHERE author = '$currentUserId'
EOD;
$stmtEditPostCheck = $pdo->prepare($sqlEditPostCheck);
$stmtEditPostCheck->execute();
$ableToEdit = false;
while ($row = $stmtEditPostCheck->fetch(PDO::FETCH_ASSOC)) {
if($editPostId === $row['id'] && $currentUserId === $row['author']) { $ableToEdit = true; }
}
if($ableToEdit === true) {
$editPost_Title = "";
$editPost_Content = "";
$sqlEditPostPreFills = <<<EOD
SELECT id, post_title, content FROM posts WHERE id="$editPostId"
EOD;
$stmtEditPost = $pdo->prepare($sqlEditPostPreFills);
$stmtEditPost->execute();
while ($row = $stmtEditPost->fetch(PDO::FETCH_ASSOC)) {
$editPost_Title = $row['post_title'];
$editPost_Content = $row['content'];
$editPostId = $row['id'];
}
$content = <<<EOD
<form action="?profile&editPost="$editPostId" method="post">
<h1>Edit Post</h1>
<div class="form-group">
<input name="Epost_title" type="text" id="Epost_title" value="$editPost_Title" class="form-control">
</div>
<div class="form-group">
<textarea class="form-control" name="Epost_content" id="Epost_content" value="" rows="6">$editPost_Content</textarea>
</div>
<div style="text-align: right;">
<button type="submit" name="update" style="width: 30%;" class="btn btn-success btn-lg">Update</button>
</div>
</form>
<hr />
EOD;
} // end IF ableToEdit
$updatedContent = "";
if(isset($_POST['Epost_content'])) { $updatedContent = $_POST['Epost_content']; }
$updatedTitle = "";
if(isset($_POST['Epost_title'])) { $updatedTitle = $_POST['Epost_title']; }
if(isset($_POST['Epost_content']) && isset($_POST['Epost_title'])) {
$sqlUpdatePost = <<<EOD
UPDATE posts SET post_title='$updatedTitle', content='$updatedContent' WHERE posts.id='$editPostId' AND posts.author='$currentUserId';
EOD;
$stmtUpdate = $pdo->prepare($sqlUpdatePost);
$stmtUpdate->execute();
}
}
// end edit post

Answer 1

This line look bad for me
<form action="?profile&editPost="$editPostId" method="post">
try to change it to
<form action="?profile&editPost=\"$editPostId\" method=\"post\">"