Brother's car wont crack just clicks

It actually really sounds like the battery. How are you charging it with a trickle charger or jumper, because if you have a bad cell those things really wont help. Try using those big speed chargers they have at like advance if you have one laying around. Put it on high for a minute and give it a go. I have a snap-on one at work and that one always does the trick. If you test the battery and it still checks out you could go str8 to the starter and short the signal to the power to get see if it cranks if it stil does nothing its the starter (assuming the battery is good) if it does work well then you have a problem with the signal to the starter but i doubt it because you are still hearing the clicking.

sounds like that battery is dead take it to auto store and have them test it.

I also think bad battery...how long has the car been sitting waiting for the donor motor? And how old was the battery before all this happend? If an old battery sits and gets discharged..theres a good chance that it will be no good. Spend 10 min. and take it to the auto parts store to get it tested. And/or bum a battery from another car (you seem to have some pretty sweet ones ) just to make sure thats not the problem. But it def. sounds like a dead battery.