2.0 tfsi rough running and rattling after timing belt change

[Melvin_C.Yowser]

I recently changed the timing belt and water pump of my 2008 Leon FR 2.0 tfsi DSG. Within seconds of starting it up, the idle became really lumpy and then started to rattle badly as if something was coming loose and then was getting close to stalling so I shut it off.. I stripped everything down again, all the timing marks were correctly in line, the pointer on the tensioner was where it should be, but as the photo shows there's a patch on the belt that looks like it's melted and the top roller is covered in debris after less than two minutes of the engine running (See photo). The car's been off road, nose up on axle stands with the battery disconnected for three months as I also changed the thermostat, which took ages and then I was down with the sickness for a month or so.. There were also no codes present when I scanned it with my Topdon code reader.. Any thoughts on what's going on and what I should to next would be really appreciated..