Help launcher on SD - won't boot

[Hogri]

I stumbled upon this forum through this thread and was relieved to find that I'm not the only person stupid enough to make such a mistake. Only I have a Sony Xperia Pro and no backup.
I also uninstalled the Home Launcher and moved my custom launcher (Nova Launcher) onto the SD. I managed to boot once since then, I don't know why it worked that one time but haven't been able to do so since then, it's stuck on the "XPERIA" screen forever and I can only turn it off by removing the battery.
I don't mind completely resetting it since all my data is backed up. I tried hard resetting it by pressing the power button and volume-down-button at the same time to boot but that doesn't work. (The only difference to booting it with only the power button is that it vibrate longer than usual when it reaches the point where I can usually enter the PIN.)

Is there a way to reset the OS to factory settings without booting it first? I'd be grateful for any tips or hints!

 

[temporary2010]

Just use Update Service or Sony PC Companion to reflash. I think those will only flash to the lastest version (Android 4.0.4). If you want to install Android 2.3.4, get Flashtool and an old ROM.

Flashtool:
http://www.flashtool.net/index.php

Stock ROM (ftf Flashtool format):
http://forum.xda-developers.com/showthread.php?t=1642480
(scroll down, down, down, to the STOCK FIRMWARES section)