sartorius scale error 53

Sartorius have an FAQ section on their website and the reply to this question is below:

The display on my weighing equipment is showing Err 53

Turn the weighing equipment off and then on

If this does not work you can email them direct with a question and they will answer you personally. The email address is on their webpage and will vary depending on which country you are in but the UK address is uk.workshop@sartorius.com.