Battery disconnected for 3 weeks and now won't start

[mitchere]

The battery on my '96 850 T5 was disconnected for 3 weeks whilst on holiday and, when we got back we couldn't open the doors either on the electronic tab (expected) or the manual door key. Only way to get in was via the tailgate and climbing over the seats to pull open the bonnet to reconnect the battery so that I could open the doors from the inside. The alarms activated but were stopped by then using the electronic tab. However, the car now refuses to start as there is no spark:
- There is fuel to the engine as the plugs are wet
- engine spins fine
- the battery is fully charged with a 12.25V charge
- the plugs have been changed for new ones
- have tried opening both drivers door and tailgate by turning key 3 times
- we've tried immobilising the immobiliser by bypassing the relays
- all wiring checked
Still no spark. Only thing left we can think of is to change the coil. Any ideas / advice would be much appreciated.

[beigg]

pop the boot off the coil and brush the contacting point clean and do the same for the existing connections off the coil as well as the wire going from coil to cap. Ensure no carbon build up and corrosion is evident on the inside of the cap [ie: electrodes within the cap] and rotor.

[mitchere]

Bypassed the 850 coil and connected one from an old 740 and it fired straight away! Can only assume it had a power surge when we reconnected the battery. Put it down to experience. At least all connections etc. are clean ready for winter cold and wet. Now off to Europarts to price up a new coil but it looks as though it might be expensive so might just attach the old 740 one more permanently.

[beigg]

A poor ground will make for a mislead bad electrical part.