After the service pack has been applied, check the entire system to ensure that everything is working correctly:
Check that all workstations are operational
Verify that all peripherals are working correctly, such as receipt printers, bar and kitchen printers, customer displays, card readers, PIN Pads, etc.
Use a training employee to test all the normal sales operations.
Logon to the back-office and test daily administration and management duties, such as verifying punch cards, taking back-office reports, etc.
If possible, test a credit and a debit transaction to ensure that all systems are up and running before customers start showing up.