The easiest way is to create a new MySQLi connection and then open existing pages and update the connection used. That should cause the code to be updated.
I can do screen sharing with you to debug this error. I'd start by reinstalling the extension, clearing the winfilecache, then reproduce the error. If it still occurs then I'd have to dig through the code to determine why. Please post a US phone number or Skype contact information if you continue to have this problem and need help debugging it.