If you have a 507 error then run the AppLoader again and that will fix that.
To me it sounds like a screen issue although if you wish to take the device apart and follow YouTube video advice the only thing you need is a T6 Torx screwdriver. Taking apart and reassembling BlackBerrys is not particularly difficult, it only requires a little bit or patience.
If you do buy a screen for it from ebay or another online retailer etc they are not difficult to fix. This video illustrates the process. YouTube - Blackberry Pearl 8100 Screen Replacement & Dissection by DirectFix.com
Alternatively any decent mobile phone repair shop should do it for you.