To rule out any problems with the cylinder try inserting your key and turn to unlock.
Multipoint door lock jammed.
If the teeth connected to the bottom hook are not in the right position then lifting the handle will not bring the hook completely out for you to open the door.
Route drill cut or remove the wood to expose the slot.
It could be 1 of 2 things.
A multipoint lock that is engaged when the handle is lifted if your door is misaligned or if there has been excessive pressure placed on the door then it can cause damage to the locks.
It can also indicate the cam has become worn.
In this video i attempt to open a patio door that has got stuck locked.
The mechanics of the lock have broken leaving the top section of the door completely.
On doors where there is a multi point locking system this can be a sign that the system has been worked too hard.
If you do not have a proper broken key extractor you can use a jigsaw blade or a pair of tweezers.
Definitely not the fault here was the multipoint mechanism this is the long locking strip in the edge of the door and in this case the gearbox the center case in the middle of the locking strip i carry most multi point gearboxes so it was simply a case of replacing the part in the door.
A door lock can also start jamming due to a lack of lubrication.
The wood can be removed from this area to expose the slot.
The bottom of the vertical slot is about 1 inch above the thumbturn cylinder slot and abou 1 4 inch off center towards the latch side of the door.
Pictured below is an example.
A broken key extractor is one of the easiest ways how to fix a door lock that is jammed in this way to open.
When you are trying to figure out how to fix a door lock that is jammed it is necessary to stay patient to avoid causing further damage.
Then insert a small screw driver awl etc.
This problem with the multi point locking system can develop over time until the lock suddenly stops working.
Sometimes the pins and levers inside a lock become so dry that they stop moving smoothly and eventually seize up.