Update problems with Desire on O2

[SamJones]

My HTC Desire said there was an update available, so I went through the rigmarole that it entailed, and now it won't boot up properly.

I have switched off, battery off etc, and managed to backup files on pc.

This was update 2.14 something not the 2.2 froyo update that caused problems last month.

Do I have to do factory reset?

Yes,fully factory restore (dh works for o2 technical support),apparently its a common problem with the htc phones?