I'm not sure how related these issues are, but in chronological order:
Couple of weeks ago car felt flat off the turbo under 2k or so, friend suggested giving maf sensor a clean, did so and it went into limp mode after refitting.
Replaced maf sensor, immediately out of limp and pulling well but with eml on - although this turned itself off after a few stop starts.
All good I thought.
Nope.
Went out last night, stopped at the shops, when I restarted the revs were stuck at 1200 on tickover and throttle gave no response at all.
Then to top it off, continued running after I turned off the ignition and removed the key with accompanying lights on the dash doing their best impression of a 1970s disco.
Limped home on 1200rpm ish, limped to work this morning the same.
Did a bit of googling, all seemed to point to wet footwells which I checked and are dry.
On trying a Bsi reset I noticed the negative battery terminal was very loose and had no doubt been arcing (perhaps causing spikes?)
When I reconnected everything (securing the loose terminal with a self tapper) the ECU was making some scary noises - like a relay clicking but much faster.
I had noticed it making an occasional noise on turning ignition on before but this was like a electrical buzzing, very noisy.
Mate at work suggested whipping ecu out and inspecting it inside for damage - sure enough as soon as I cracked the thing open I could smell that awful burning circuit smell and there was a large amount of burned circuit board around the middle of where the pins join the board.
I'm at a bit of a loss. I can only assume the ecu was burned out by the battery terminal problem. It was jump started a couple of times in the summer too, but I guess the terminal being loose for so long has gradually buggered the ecu possibly taking out the maf sensor before that.
Looking on Ebay for ECUs I can't find an exact match for my part number (281 001 977) - closest I can find is one number out (978 on the end) and I've noticed some people sell them with BSi and key, some just ECU and chassis number for car it came from and some just ECU on their own.
What are my options for sorting this? I'm assuming any replacement ECU need telling with a computer to play nicely with the car?
I've got half a mind to just cut my losses before it turns into a money pit, as I'm due an MOT in the new year and I already know I need a flexi and engine mount. Cambelt interval looming too. But it's such a good car otherwise it'd be a bloody shame.
Dilemma I have is: is it worth spending 30-100 quid on anything from ECU to full ECU/BSI/Key combo plus whatever it'll cost to get them to talk to my car?
I preferred shoestring motoring before all this electronic bollocks...bangernomics are starting to look like a ponzi scheme!
Any advice would be greatly appreciated. I've had better Fridays...
) SOLD I've sorted the airbag light 
)
run's for cover 
