There are few things that a person can do for fixing a DSLR camera.

First is always make sure that the battery is charged.

Then try another memory card.

All cameras has a camera reset - that resets the camera to factory settings.
That resolves many problems caused by accidentallyidently setting something that may cause other problems.
Read the User Manual to find the factory reset.

The User Manual usually contains the phone number/email address of the Service Location for that camera.