Everything is now working.
(1) I was not aware of having removed any jquery scripts.
(2) The username (for the smtp mail server_ should have ended in ".fm", not ".com".
(3) For some reason, universal email template had changed from "Block_7.php" to "BLock_6.php".
Once I had done those three things, and also did as you instructed and (a) commented out the debug line, and (b) de-commented the email close line, everything started working.
Thank you again.