Pickersgill

Hello my wife's car recently wouldn't start. After driving it for a few hours in the afternoon we came home, then 20mins later went to go out and the car wouldn't turn over. At first it seemed like a flat battery; no interior lights, dash lights wouldn't come on etc. Strange thing is after a few seconds or so the dash would come on and so would the interior lights, though the headlights don't work. I go to crank it over after I wait for the dash to illuminate and when I turn the key the dash goes black similar to when you have a dead battery and a clicking noise comes from the ECU. I release the key and the dash lights back up after a second or two and then the lights kind of flicker for a bit. I've checked the voltage on the battery and cleaned the terminals. Next thing i'm looking to do is try check over the ignition fuses and then look to jump start the engine If you have any ideas or help please that would be great, even just a some direction as to where to look next. Thankyou