Hi, I've got completely dead electrics on my mk3 focus diesel - left lights on over 2 days, now not a sign of life on the dash despite attempting to jump start, with new key fob battery - the only sign of life being the red information light at base of console lights up briefly when turning the key or operating key fob. Have tried reset procedure in the door lock for immobiliser twice with no luck. Ran jump leads for 25 mins with revs - at least the info light is now brighter and batt. now has a small charge, but still no response when jumping and turning ig. key.  I suspect the immobiliser has gone into dead battery anti theft lockout but can't get it to reset - has anyone got any ideas? 

Just read a bit more in this and it seems the red i warning is obv. immobiliser not info.

Further methods not working;

   Turn key 8 times in 10 seconds then initiate start - this to reconfigure key - doesn't work.

  Turn key 4 times in 8 secs to 2nd key position - this to disarm immobiliser - this also doesn't work.

  This all with 12.5 v while jumping another battery.

I'm out of ideas from googling this, anybody else got a clue? Thanks in advance. 

I had something similar, the car wouldn't turn over even after I'd had the battery on the charger overnight. Turned out a new battery was needed.

Jumping from another battery gives a false reading.  I'm guessing the voltage drops considerably when you remove the jumper cables?

As above, I'm fairly sure the battery will have been totally knackered after such a deep voltage drop and will now need replacement.  You're welcome to have it tested (for free) somewhere like Kwik Fit first.