Ignition won't turn when i put the key in
 

Hi, I am in the UK and there are not many places to get any help with H2's! I got out of my 2003 on Saturday evening to pick something up, all appeared the same as usual. Went back unlocked my car but the key in the ignition and it wouldn't turn. The dismount mode worked when I pulled the key out again. And when I put the key in the loud (you're in gear) beeping goes off. Checked wiring under the centre console and repaired the green and white one, checked that shift linkage was not disconnected.
Can anybody give any advice as Hummer mechanics are as rare as they come over here Txs