how can I fix my Iveco Tector ?

Help Iveco Tector
Can any one shed any light on a problem I have with a 02 Iveco Tector, It want turn on the key, I came to it and the battery was flattish it turned a couple of times slow and stopped, so I tried jumping it and that didn't work so I took the batteries off charged them up and now there's nothing on the key, all the dash lights come on but its as if the starter isn't there, I've hot wired it direct and it turns but, not on the Key. I've had Iveco out to it with a computer ( a 15 year old) and he said the computer wouldn't talk to the truck, that cost me 180 quid.