2005 Gen 1 Won't turn off.

Hi, I was wondering if anyone could help as all was fine and dandy until.......
battery died the other day as I checked the oil, plugged tricle charger in and all was good. As you do on a sunny day got up to go to work, battery dead. rev counter needle just twitching with no dash lichts on.
bought higher CCA battery which wqas a bit taller but fitted fine. Changer starter relay for the Yam R1 one while I was at it.
Started first time, set the dash again and it turned off and all was good.
Got up this morning to go to work, started first time until I went to put fuel in. Turned the key to off and it wouldnt switch off. kept trying to turn over as though I was pressing the ignition switch.
rode back home and tried again via the kill switch but same results. had to leave on tick over until i disconnected the battery.
As soon as I touch the + terminal with the Power lead it starts to turn over even without the key in the ignition.

I've heard the immobilizer issue but don't know where its located or if you can disable it to see if its that thats the issue.

Hoping for some advice if possible.

craig.

apologies for the spelling but rushing around having to sort bike then take car to work without being late.

When I say won't turn off I meant the engine will stop running but starter keeps turning over. Doh

There's me thinking that getting the part from a m/c parts dealer wouldn't result in Chinese crap. Wrong, seems you were right Paul, put original back on and normal service resumed. Apart from taking it for a run, turned it off and alarm went off. Lol. Otherwise all is good.