We found the solution! Actually there were some screws around the sun deck to fix the Vinyl protection, screws accessible from outside all around the sun deck. Underneath the vinyl, there is like a soft pad between the Vinyle and a wood board. In the middle of the sun deck under the soft pad there are 2 screws, holding the hook. I removed these 2 screws to detach the hook underneath, then I was able to open the sundeck.
And I fixed back the cable to the locker system. The end of the cable finishing with a small steel cylinder was brocken. I was able to fix back the screw on the remaing piece of the cable to attach the cable to the locker.
It would have been easier to explain with pictures.... The tricky part was the first two steps to open the sun deck. My friend Christian found the solution Thank you !
It was actually the only way to access the engine compartment. The back seats are fixed from inside the engine compartment.
Thank you for your support guys, indeed Maxum technical team would have supported us for sure. We found alone - satisfaction ;-)