Vauxhall Astra wont start

Had to jump start my car after it sat for ages and it started fine. I left it running for a while but tried to jump start again later and it wouldn’t even turn over. The interior light was flashing like a strobe and every icon on the dashboard was lit up. They stayed on after I took the keys out and locked the door manually. The fob won’t open or lock the doors anymore, interior is still lit up and I’ve no idea what’s causing this. Is this electrical, a duff battery or the immobiliser ( since I can’t open or lock the car) Any ideas?