Picture. The unit was not used for a few months. Whenever it is switched on the screen now only

Question

The unit was not used for a few months. Whenever it is switched on the screen now only flashes up briefly. Sound etc is okay. If you flick the button at top right corner you can make the screen flash up and occasionally it will last more than a few seconds. Unit it is out warranty but little used. - fault present whether on battery or mains adapter power