Ok my turn,happened last night 3rl,went to pdftown.com/pdf-ebook/XBOX%20360%20Repair.pdf and did as it said on tin and worked first time.
Hope this helps someone else probably posted b4 as is xclamp fix but shows you exactly what to do.
Will let you know how long it lasts,hopefully a long time lol
My fault code was 0020.