well he needs to learn to sbf first, its a step by step simple process that takes about 10-15 mins and uses somewhat 10% battery life, but its always best to make sure you have it charged at least 70% cause if your phone dies during this process i have heard it is actually impossible to restore it, but iim not willing to test that theory with my phone
rooolers guide is the best and easiest to understand, in his guide he includes the files you need, for you, make sure you get the full sbf 2.3.340 it will return you to stock froyo, reactivate the phone, and as a precaution that i tell everyone to do, make sure all traces of previous rom are removed, and so is superuser, restore all your apps, and uninstall root only apps, and then you can return the phone.