It sounds like the camera firmware needs to be reset to the start.
First check the USB cable socket on the camera for any bent pins.
Then plug-in a cable.
Unplug the cable.
If that does not clear the problem:
Maybe the battery needs charging.
Charge the battery.
If the problem is still there then:
Remove the camera battery.
Wait for one minute.
Reinstall the battery.
Go to page 34 of the Instruction Manual and do a reset to factory settings.
If that does not clear the problem it is time to contact Olympus service.
If the camera is less than a year old, your camera is still under Olympus warranty.