2004 Jaguar X-Type Possible ECM replacement

Hi -

My 04 x-type is throwing about 14 codes. My non jag mechanic said it is most likely the computer or a wiring issue. I drove it longer than I should have with a bad bank 1 sensor 2 O2 sensor - and when it was replaced the wire covering had broken down and there had been contact between the wires. Once the O2 sensor was replaced the service engine light stayed on and kept saying that the new sensor was bad.

Jag told him at the time that that meant there was an issue with that chip. But not a problem.

NOW About 5K miles later -- I went in to make sure
the only code it was throwing was the O2 sensor and there are 14 codes - ranging from battery start up issues, the 2 4 6 intermittent missfires (opps had gone back to using premium and I the fuel rail absorbed to much water-)

One of the multiple codes 1646 the computer chip for the bank one sensor 2 O2 sensor.

so in my complete lack of wisdom I have determined that I probably screwed up the computer at this point.

Now how hard is it to replace the ECM unit - where is the bloody thing to start? Are there really several out there for the x-type and do I have to tow it to Jag to have it "flashed" before it will run?

I realize that I could have a wiring short - that might have screwed up the computer -- I was hoping the O2 sensor issue is the one that started this mess.

I neglected to mention that at this point the car is still running great--

Thank you for any ideas- comments anything that might help me decide if I can do this myself (i do have some skills) if I should consider a jag dealer for the repair or just dump it and get a new one,
thank you
MK