Before buying a new catch confirm that the wiring is sound in the boot hatch cable duct
What you will need........

New boot catch mechanism fiat part number #55702917
10mm spanner or socket set
PZ2 pozzi drive screw driver..
New lock
bit of grease for the threads if you have some..
Estimated time 10 -15 mins with odd slurp of tea..
remove the metal catch as you wont need this (press the little tab on the side of the lock to release it) (watch it as it fly out)

Lets get cracking...
First open the boot if it wont open see your handbook for the way to override the lock from inside the boot...
Once your in to the boot....
remove the 1x pozzi screw from in the grab handle

next remove the boot cover get your fingers between it and the boot and carefully work your way round releasing it from its plastic tit retaining clips...


And place cover to one side

Now you have exposed the lock as best you can take your 10 mm spanner and remove these 2 bolts

and withdraw lock inside the boot lid

Next unclip the cable...

refit new one in reverse order... (just ensure you put it in the correct way round
.. 
What you will need........

New boot catch mechanism fiat part number #55702917
10mm spanner or socket set
PZ2 pozzi drive screw driver..
New lock
bit of grease for the threads if you have some..
Estimated time 10 -15 mins with odd slurp of tea..
remove the metal catch as you wont need this (press the little tab on the side of the lock to release it) (watch it as it fly out)

Lets get cracking...
First open the boot if it wont open see your handbook for the way to override the lock from inside the boot...
Once your in to the boot....
remove the 1x pozzi screw from in the grab handle

next remove the boot cover get your fingers between it and the boot and carefully work your way round releasing it from its plastic tit retaining clips...


And place cover to one side

Now you have exposed the lock as best you can take your 10 mm spanner and remove these 2 bolts

and withdraw lock inside the boot lid

Next unclip the cable...

refit new one in reverse order... (just ensure you put it in the correct way round