2002 Ford Escort Battery Posts Extenders

Resently I replaced the alternator in my ford taurus and when we tried to charge the battery it wouldn't charge. What we did was crank the escort zx2 and switch the batteries. Since the battery had the taurus running, we left that one in the taurus and went to buy one for the escort. Here is where the problem begins, after we purchased the battery, we were not able to get the positive end loosend because the bolt was too tight and nothing we tried would work. We were instructed by this part start chain!That we should cut the thick part of the positve wire and connect these extenders and bolt it down, well also there is a little black box that's connected, well we were also told to cut it and replace it well, we tried several times to charge it no charge please help me