sexr3i

2004 V40 been off the road for extensive bodywork (just got the doors, dash etc re-fitted and tried to fire it). Battery in car and keyfob have been disconnected/gone flat, now the car is reassembled with new airbags and airbag module, new batteries in car and fob, and we seem to have immobilizer issues. Car won't unlock off fob but does from key and the engine won't crank but ign lights are on. Immobilizer is staying on? what to check? There's a button on the dash for the immobilizer under the heated seats and aircon ones that's not lighting up when used too. Checked all boxes, fuses, relays etc and can only think we've either missed an antenna, or it's something to do with the battery being off for so long. Apparently the key codes are "rolling" so have they gone out of sync maybe? Any literature we've found just says go straight to a dealer, but we havent finished the car totally yet so are looking into it ourselves, if anyone could help it'd be much appreciated.