Can anyone help? S-Type won't start.

[VirtualMark]

Hi.  I am currently in possession of my girlfriend's dad's S-Type.  He's a bit old to be driving now and I said I'd sell it for him.  We drove the car to my house, everything was working fine. 

Went to start it the other day and it won't turn over, the steering is locked too so I can't move it.  The LED is flashing, further research shows that it's code 11, B1681 - PATS Transceiver Module Signal Is Not Received.

My friend is a mechanic and put a diagnostic reader on it, but couldn't find the PATS system.  So I'm thinking that there must be a faulty connection to the PATS module?  The thing is, I have no clue where it'd be located in the car. 

Can anyone help?  Maybe point me in the right direction, things to check etc. 

I have noticed there's water getting into the boot, under the spare wheel.  Could this have caused the problem?  The PATS fuse is in the driver's footwell so I'd be surprised if it had, but thought it was worth mentioning.

Any help would be greatly appreciated, I'd like to get it started rather than having to sell it for scrap.

Thanks.