I have problem with my TX2,
When I press start button both green led operate, as soon as I release they turned off.
Nevertheless, the operating system does not work at all, even if I keep my press.
This sounds like a hardware issue. If you have the same behavior after removing anything external which might consume power, e.g., USB, does this still occur? If so, then I think you have a bad carrier board. If you have another module or another carrier board, then you could try swapping and see if the issue follows the module or the carrier board. Very likely the issue follows the carrier board.