headlining and replacing remote receiver box

My remote unlocking and more importantly alarm/immobilser is becoming less reliable and appears to be adversely affected by the wet weather.

Looks like its time to drop the roof lining and replace the remote receiver, so a couple of questions:

- How long is it likely to take me to get the roof lining down?
- Could I replace the remote unit just by dropping the back part? The Disco is a non sunroof variety
- Is there aset procedure for replacing the receiver, is it plug and play or do I need to disconnect the battery or take other actions?

Cant decide whether to get the whole lining down and remove the sagging material and just paint it as others have done..................

UPDATE
Just got home and remote wont reset so I cany disable the alarm or imobilser! If I open the door alarm triggers and putting the key in the ignition doesn't stop it! Engine wont start of course!........any ideas?

1. That depends on how sharp the blade in your Stanley knife is.

2. I would think so, as that's what can be done 'carefully' if u had a rear sunroof problem.

3. Plug but I don't know about the Play bit, but it's good practise to isolate anything that's electrical first.

Have you changed the battery in your key fob?

yes new batteries in both fobs. It's actually the car that forgets the link with the key. It's possible its a poor earth on the receiver box but I wont know until I actually get to it. There was a landrover update on this but I think the unit is affected by damp it was fine for ages when it was hot but has started playing up again now it's wet!

OK time for an update. Disconnected the battery to kill the alarm and dropped the headlining. It was clear that the earth tag to the receiver box had not been connected from new! Since I had the new unit I replaced it with the earth tag this time, reconnected the battery and it now works perfectly, with the key being effective at much greater range than before.

Ripped all the sagging material off the headlining and painted it, not perfect but way better than it was.