It depends on the model. For the MX707TC and MX708TC you press Cancel on its own and then 5 and 7 together to set the lock, and 5 and 7 together to unlock again.
Claire Jordan, September 2012
HIYA IVE ALSO GOT A HINARI MICROWAVE I THINK MINES BROKE. HOW DO YOU KNOW IF THE CHILDLOCKS ON? PLEASE EMAIL ME AT nataliebrown7487@yahoo.co.uk thanks