The camera is showing this message because it has detected a bad state. The turning off and on can clear up temporary states but sometimes you have to go further by also removing the batter and memory card. Try again after leaving out the battery for a min or two. No need to insert the memory card as that will add another potential point of failure.
If it powers on without showing the error message after reinserting the battery, then add the memory card back to see if it causes the error. If it does, you can reformat it on most computers with a card reader or just replace it.
If it shows again the error message then the camera has a default which causes it to be in a bad state and you will have to get it serviced professionally or replace it. Always ask the price first before agreeing on the repair. For low-end products, it can cost as much to fix as getting a new one! Or at least buying a working used model.