Ok these washers have a problem with the door locks sticking. But usually banging the door releases it.
Have you tried turning the power off the washer and waiting a few minutes then banging the door?
If its still not opening then what you need to do is remove the top and from there look down the front on the inside on the right hand side.
There you will see the door lock. Poking through this on the left hand side of the lock is the door pin. You may not see it but feel around and you should feel it.
Push this door pin to the left and at the same time pull the door handle and see if it will open.
If not then you need to break the door lock off the washer to release the door and open it.
To be honest its very rare ive hand to break the lock to open it as banging it messing with the lock from the inside releases it.
Once you have it off you need to replace the lock. Now the new lock will look different but is the same. They have just changed the design of the lock because they were failing a lot on these for this fault not releaseing.
So try the above and you should mangage to get it open from there.
If you need anymore info just get back to me.