Can you skip through the programme to drain? Press pause button. then press start to move the lights down to the empty cycle. leave to finish.If you have already tried this, I can explain how to put machine into engineer test mode, which will then give out a fault code to identify problem.
Other interlocks have a secondary locking system which ties in with the pressure switch - the mechanism which detects if there is water present in the drum. If this system is faulty - caused by blockages in the filter, pressure vessel or the thin rubber pipe running to the pressure switch the machine "thinks" its still full of water and wont allow the door to be opened. Take off the top cover, examine the interlock from behind and detach any rubber pipes or cables to try to open it from inside. If all else fails, the interlock itself may be faulty and will have to be broken open. A replacement interlock unit and/or catch will of course be required.
Basically you will need to remove the top and with a screwdriver pop the latch.
You will need to replace that part but it is easy to do, and I will help you with this. Idf you will rate me today before you leave as good service or better, the system will allow me to schedule free follow ups with you so we can remain on this question and it will not cost you anything further:-) Thank you Tech Michael