citreon dispatch wont start?

hi can anyone help please my citreon dispatch has been on the drive for 5 months without being started. i went to start it and the dash lights came on but when i turned the key to start it just click. i thought the battery might be flat so i removed it from the vehicle and charged it overnight, next day reinstalled the battery and tried again and nothing, took it out again and took it to a garage to test it and he said it was ok. i even bought a new battery and tried again but nothing. i had a mobile garage come out and he checked all the fuses connected his analyser but says he couldnt accsess the ecu and gave up. any ideas?