Car dead with a new battery
 

Have a really weird issue going on. 2010 Sebring Limited with 2.4 lire engine. Replaced battery and alternator about 6 weeks ago. Car involved in low speed frontal collision on Labor day with minor damage to hood and front bumper cover. Car is still drivable. About three weeks ago son tried to start car and had no power to the car. No lights, no horn, no electrical power at all. Confirmed lights were not left on. Volt meter to the jump posts under the hood showed about 3.5-4.5 volts. Battery shows full charge with volt meter. Unhooked ground cable at the jump post and cleaned terminal end. Checked a few more items under the hood and after about 30 minutes hooked battery ground back up to the jump post and now car has full power and starts as normal. Alternator charging at 14+ volts as expected. Turned car off and on numerous times afterwards with no issues. After doing some work on the car yesterday I went back and cleaned the ground terminals again both at the bulkhead and engine block. After starting the car a few more times went to move it out of the garage and when I turned the key I heard a click and then now power. Same situation presented itself as before. Had to unhook battery ground and let car sit for about 30 minutes before reconnecting the cable at which time it started fine. What is going on with this car?