but I was unable to get the tuner to work (either the single
tuner or the twin) the program crash.

Connect the box with the serial cable, and check with a terminal program as Putty why the tuners crashes.
And it could help if you give a picture of the twin tuner, both sides.

Software...
But crashes are mostly related due software.
Best is to flash the box with a reliable old image file to see if at least the normal tuner works.
Twin tuner is a different story and may need a extra driver.

But again, check it with a serial port terminal program.

What if it's a hardware failure..
At this moment, and to think of if it's a hardware failure, than my best shot is that it may related to a weak voltage.
Maybe the 12v power supply, or one of the Dc to Dc ic's.
Nevertheless it's a guess, because without more info it's hard to say what it could be.