what PeterRST said

if the key has been turned then you are looking at the inner working being fucked at some point

we had this on ne of our connects, it ran fine for about an hour then it was fucked
so we drained the pertrol out and put in diesel and it seemed to be fine again
but after about 3 weeks it was properly fucked again and needed £3k spent on the fuel system to get it sorted, we got it done under warranty and sacked the guy who put it in