Is there such a thing as touchscreen calibration I have bought a generic touchscreen replacement (not the actual screen where pixels are drawn, but rather the touch sensor where touches are captured) for my Defy/MB525, and replaced it myself. 

It doesn't work, it seems to register many random touches in a few seconds (while the charger is disconnected, and no screen protection films are present). I know I probably either did something wrong or got a malfunctioning touchscreen, but maybe I'm missing something? 

Do I need to perform some calibration? If so, how can I proceed? My phone is asking for a locking code and I can't enter it as it is.
As you asked for a calibration tool: The Playstore seems to have some suitable candidates, e.g. Touch sensitivity calibration. But while this might be helpful, the permissions look quite suspect: The only job of the app is screen calibration, but it requests permissions such as accessing your contacts, call phone numbers, read and send SMS/MMS, and more -- according to a screenshot on the apps page at Google Play. Funnily, the permissions tab says differently: No permissions required... So I'd give it a try, and abort installation in case those permissions really turn up.