The subject line says it all really - I have a 2G (history unknown but looks in excellent shape and the water sensor isn't showing red), which will only boot when I hold down the sleep/wake (power) AND home buttons at the same time - and for quite a while at that.

The thing doesn't power-on simply by holding the sleep/wake (power) button no matter how long I hold it. Not does it come up in recovery when I hold the home & connect to the Mac and unsurprisingly I can't get it into DFU either.

Interestingly if I do the trick of holding the power / home buttons for some time it will boot into recovery mode and iTunes can proceed to updating & restoring 2.2.1. Although the phone switches off around half way through the restore process.

Does anyone have any suggestions?