Every time access is gained to a logic area of gaming equipment, a record must be made in the logbook kept inside the gaming equipment cabinet or secured near the gaming equipment, detailing

the reason for the access;
the name and licence number of the person accessing the logic area and
the work done.

See Chapter 6.1 Gaming Prohibited on Unprotected Devices

Industry participants can access, via the following link, a template for a logbook: Logbook for Gaming Equipment (Technician Logbook) (PDF: 45KB). Venues may wish to produce their own logbook. However, the template indicates the minimum details required in a suggested format.