Question about Steffen digital brilliant

I bought the unit now and it only ran for one day. Now it doesn't let any power through. When I unplug it and plug it directly into the socket, it supplies power. This poses a problem for me that the unit is causing more problems than it should serve. I have set the time. Now when I press the Up/Down TimeOn button it shows me 23:59 Hours.... And I can't change that. The instruction manual doesn't know about this power lock function. Maybe it's a child lock and I, as an adult, have to give it to a child to make it work? am frustrated at the money thrown out