Hey
There are some locks that can't be opened from the top. Knowing whirlpool this would be one. So we now know the pump is not blocked.
Right if you can locate the vacuum switch we can release the tube. Most machines this looks like a round disc, but on others the shape can vary. It will have a very tiny tube attached to it. Maybe you can take photos of the top and the back if you can't see it? If its the round disc version they tend to be at the top, the other versions tend to sit somewhere near the motor at the bottom. If we can release that tube we know its not the vacuum.
So its not blocked as you can blow down the grey pipe. That leaves 3 things imo.
1) Vacuum is blocked so its telling the machine its full of water.
2) The lock itself wont release so the lock is broken
this one is pretty rare but the 3rd is the programmer itself that is not sending the information to the door lock.
This is a vacuum switch on an old Hotpoint, underneath it has a little tube attached.

It might look different on yours. Apart from this there is not much more that can be added I don't think. But saying that it has been a long time since I was a repair man
I am sure the insides have changed a lot over the years.
---------- Post added at 21:15 ---------- Previous post was at 21:13 ----------
One more thing to add, can you see the wires going to the door lock? These also tend to get brittle and snap.
Other then that its very hard to see the problem without actually seeing the machine. For me anyway
There are some locks that can't be opened from the top. Knowing whirlpool this would be one. So we now know the pump is not blocked.
Right if you can locate the vacuum switch we can release the tube. Most machines this looks like a round disc, but on others the shape can vary. It will have a very tiny tube attached to it. Maybe you can take photos of the top and the back if you can't see it? If its the round disc version they tend to be at the top, the other versions tend to sit somewhere near the motor at the bottom. If we can release that tube we know its not the vacuum.
So its not blocked as you can blow down the grey pipe. That leaves 3 things imo.
1) Vacuum is blocked so its telling the machine its full of water.
2) The lock itself wont release so the lock is broken
this one is pretty rare but the 3rd is the programmer itself that is not sending the information to the door lock.
This is a vacuum switch on an old Hotpoint, underneath it has a little tube attached.

It might look different on yours. Apart from this there is not much more that can be added I don't think. But saying that it has been a long time since I was a repair man
---------- Post added at 21:15 ---------- Previous post was at 21:13 ----------
One more thing to add, can you see the wires going to the door lock? These also tend to get brittle and snap.
Other then that its very hard to see the problem without actually seeing the machine. For me anyway