I've checked as suggested by Zax and here is the result:
1/ The lens assembly seems simple and solid. There is no loose part as I can see (see attached image)
2/ Video clip showing the laser is focussed but it is weak. Also as I indicated from the beginning... I don't have the "weak light" anymore. Each time I press the weak light button the LED just flashing red but there is no laser at all.
Here is the video link: https://drive.google.com/open?id=1nezO3MtnYctH9IdM1vvM6u7sqMnOHFD0!
@davidwoodworker There are many options for software, I wrote T2Laser as an alternative and provide support for it as well as constant development. EleksCAM is obsolete (only works with the older firmware) and unsupported (has known bugs that aren't fixed).
The Nano is a standard device with many alternatives, they are plug and play replacements. I have used Geekcreit, HiLetGo and others with good results - these all use genuine ATmega328p microcontroller's which are more reliable than the Chinese copies.
Just bought mine A3 and start testing. Mine is only last a couple of tests and have the same problem like this poster has. I wonder if anyone has the answer yet. I really regret to buy this piece of s***. I feel like we have been cheated.