Starting problem

My L&K 2010 Octavia Estate has been running ok and usually starts first time. This morning however turn the key and nothing, no warning lights, no radio, completely blank panels. Have connected battery charger which says battery is 80% which I assume should be enough to start the engine. I disconnected the charger and the radio worked and warning lights came on but no start. Warning lights started flickering intermittently. Charger reconnected and I will try again when the battery is fully charged. Any ideas would be welcomed as the only thing I can think of is a stuck starter solenoid.