Stumped, 2005 Skoda Fabia stereo

Hi,

I am trying to fit a Sony stereo ( Sony CDX-GT100/GT111 CD Tuner) in a Skoda Fabia (2005 classic).

When first connected it worked and i tuned in the stations. Then after switching off and removing fascia to slide the stereo in, i switched it back on and nothing happens. I checked the fuses and returned the unit to the shop where they tested it on a rig. It worked fine.

I later tried the factory stereo in the fabia and it worked fine.

Any ideas what the problem may be?

Thanks in advance

Ross