AEG 44050 VI dishwasher refuses to fill

Hi, first time post…

I recently bought this 2nd hand integrated dishwasher, the AEG 44050 VI, to replace my free-standing Bosch.
I’m fairy certain it was working when I bought it, but when I connected it up and started the first load it got part way through the cycle then gave 3 beeps and seemed to get stuck on the drain cycle. The manual says to call a repair man. Googling tells me it’s the anti-flood tripped in.

I didn’t find a way of curing that, despite taking the sides off and making sure the anti-flood switch was ok. Thinking back, when the 3 beeps started I was emptying the sink and maybe the washing machine outlet wasn’t draining fast enough. Not sure, but anyway I gave up and reconnected my old machine to get back to a working state.

Now, some days later I’m retrying to get the AEG to work. When I start it up it gives one beep and fails to fill. If I switch off and on and restart and press the cycle button again it immediately goes to the 3 beeps again and goes into perpetual drain mode.

I don’t think the inlet valve is faulty (it did fill first time, the filter is clean, water pressure is ok), so I’m wondering if it’s stuck in some “anti-flood” mode. Is there a way to hard reset the machine to get past this? A CTRL-ALT-DEL kinda equivalent? 🙂

Any suggestion? All suggestion gratefully received.

Thanks, John