Bosch WAE24162GB/03 not emptying – alarm, won’t start any pr

I’ve got a Bosch WAE24162GB/03 washing machine that has worked fine for about 6 years. Today came home to find it stopped, full of water and door unlocked. Tried to start again but on all programmes will sit in silence for about 30 seconds then get an alam type beep – 3 lots of 4 short beeps. I’ve emptied the water manually, cleaned the filter and the pump looks clear – the pump rotor spins by hand. Emptied machine of washing and water then tried again. Same problem – all programmes will sit for about 30 seconds then get alarm of 3 lots of 4 short beeps.

Any idea what the problem might be? First thought was broken drain pump, can anyone confirm this?

MAny thanks