How to start a sl500 after you change batteries or engines?

i put a new engine in a 2004 sl 500 it wont crank or change gears wanted to put in in nutral to push car but cantHow to start a sl500 after you change batteries or engines?
If the battery has been sitting around a long time and is over 4 years old, you'll be better off buying a new battery that will hold a charge much better than an old battery. You can also buy a battery charger to keep it fully charged to 12.65 volts measured with a Digital Multi-Meter (DMM) like the Sears DMMs below. Clean the battery cable connectors with the wire brush type (link below).



http://www.jcwhitney.com/autoparts/Produ

http://www.sears.com/shc/s/p_10153_12605

http://www.ehow.com/how_512_replace-car-

http://www.sears.com/shc/s/search_10153_