My 2008 FL2 has not been used for about 2 months, it's just been parked up on my drive, it's due for MOT in a couple of weeks so this morning I thought I'd best see if it still starts OK, I pressed the unlock button on the keyfob and nothing happens

Oh I thought, the battery must have gone flat, it's parked up very close to a shed but I managed to get the emergency key in and opened the passenger door a couple of inches which set the alarm off, hazard lights and all so clearly the battery is not flat!

Next thought was the keyfob battery, I tried my spare and that was the same, on opening the fob cases I found the batteries both showing just over 3 volts with a tiny drop when a button is pressed.

Both fob batteries and the main car battery were replaced less than 2 years ago and all appear to be working, both fobs were working normally as was the rest of the car until I stopped using it a couple of months ago.

Is it possible for the keys to "lose" their pairing with the alarm ECU? (or vice-versa.) ?
I could really do with finding a solution that doesn't involve dismantling the shed to get enough room to get in through the passenger door.

If the cars been standing for 2 months I'd expect the batter to be pretty flat even if the alarm works. I'd first try and get access to the battery to charge it. The bonnet release is the passenger foot well is it possible to get the that or hook something on to it. Only and idea!?

Did you put the key fob in the slot and press start. The FL2 Battery Management system is designed to cut supplies to everything accept the Perimeter Alarm after about 28 - 30 days.
This should protect the battery from going completely flat and the car normally starts.

Look at my posting on this thread.
http://www.freel2.com/forum/topic28745.html FL2 XS SD4 Auto 2010 2012-2017 (21k - 91k miles) (MY2011)
FL2 Metropolis SD4 Auto 2014 2017- (16k - 77k+ miles) (MY2015)
Metro in its 11th Year of (Extended) LR Warranty / Full LR Service History
(Expensive, but Trouble/Worry free - hopefully?)

Sorted!! thanks to all for your comments.

Unfortunately, getting in through the passenger door was initially not an option due to the close proximity of the shed I'd parked next to, the only thing I did manage was prodding the unlock button on the dash with a long stick through a small gap, this, however, failed to achieve anything.

Searching the forum a bit further though revealed a post mentioning the car's battery saving "hibernate" mode as Ian mentioned.

Fortunately, I was able to get my Defender in front of the FL, I attached a strap and dragged it just far enough forward (it's an auto in "P") to get the door open. I docked the key which turned off the alarm and allowed me to start the car normally - big relief

So I guess the moral of the story is - if you're going to leave the car unused for more than a month, at least leave it where you can access the passenger door