Hi
it sounds like it is all BeCM related, the module that looks after security etc. The reason the battery goes flat after one day is that the BeCM is being woken up continously by a neighbours/your wireless network, wireless doorbell, wireless security system etc. operating on the same frequency as the remote. This is very common, do as search under 'flat battery' amd better explanations and fixes are on this forum.
The battery going flat may have confused/damaged the BeCM resulting in the errors you are experiencing.
Look under BeCM in this forum for more information on that.
Also rangerovers.net is a superb american site for common (and this is) problems and fixes.
Cheers
Adam