L515 is not recognized

I bought a L515 few months ago in replacement of another L515 which has stop working. This one was first working perfectly and we were using it with the SDK on linux. But some day, I get an error from the hardware notification log windows: "Frames didn't arrived within 5 seconds". This time I tried:

- update the firmware
- reset hardware
- test on another computer on windows 10 (I got the same result)

One month later, without doing anything, the camera was suddenly working without returning any error but only for few weeks. 

Indeed, now, the camera is not even recognized by the computer. The command lsusb doesn't return the device (tested on two computer and with two different cable) and the command dmesg doesn't return anything related to the camera.

Sometimes, the camera works but most of the time it doesn't.

Is the camera broken ? Are we doing something wrong that corrupt the driver ?

As I have just said, it is our second camera of this model which doesn't work. We have also used the D435 without having any trouble. What from this camera is different from the D435 for not being able to use it ?

Thank you