Help! Any phone tech people on here?

Here's the lowdown on how much of an idiot I am:

I attempted to unlock my Sony Xperia X10, however just before it finished the program froze and was forced shut by windows (Multi Unlock Client).  So, my phone was left partially locked.  It could read my sim card, but couldn't connect to a network (both my network and a foreign network).

Here's my stupidity part:

Someone recommended doing a Sony update / repair.  So, I went through and did this, however now that I've restarted the phone, all I get is a blue screen with the little bar at the top that tells time, battery, that my sim is locked and battery status. If I plug the phone into the computer it will recognise it and come up with a screen to connect to the computer and is responsive in that respect, but if I back out it just returns to the blue screen.  It does time out and go dark too.

Can anyone recommend anything or should I just fork out the stupid cash this is going to cost and take it into a repair shop to be fixed?

Sounds like a bad flash.  I don't know about the Xperia specifically, but in general on Android devices the system and the data are on separate partitions.  A factory reset only clears the data, so if the system partition is incomplete (a possibility since it sounds like your computer ended the flash early) then a simple reset won't fix it. 

So try starting from scratch, flash a factory image and see if that gets it going.  Then, root and unlock if necessary.

Also, for security reasons make sure your phone is updated to the latest Gingerbread 2.3 release, not Donut 1.6 or Eclair 2.1.