Hello I had problems with the 12v battery, it was drained and I had to recharge it, which meant disconnecting the negative/ground/earth cable. Ever since the rear door opening button on the outside of the car won't work. Any clues, I tried searching the forum but didn't find anything.
Not necessary to disconnect anything when charging the battery. Use the front jump points under the hood in the black plastic fuse box on the right. Flip up the red plastic cover. That's the positive terminal. Bolt that holds the strut on is negative. Charge my battery all the time. To open rear hatch crawl in the back. Open the floor hatch cover and there's a manual lock release on the bottom of the hatch area. Its in the owners manual. Many posts about it on this site.