According to the break-down guide for the i3:
• To bring the vehicle out of a danger zone, you may pull it extremely slowly over a short distance
of no more than 500 m. If possible, make it rollable first by switching the selector lever to N.
You may need to find a towing company that has wheel dollies. They are used to roll cars out of tight parking spaces and parking garages that tow trucks can't easily get into.
https://www.youtube.com/watch?v=IaMJB88XWnI
Have you let it sit overnight plugged in to charge? The car's computers sometimes needs time to reset after a battery swap. On a lot of the tools used for battery registration you can look for error notices, and reset them, which can help 'wake up' the car as well.