Battery saver function activated and lost all electrical power

While driving home the other day battery saver function activated. I get home turn car off go to truck to unload groceries and trunk won't open and alarm remote not working. So I got back in and tried to start it again and nothing no beeps no dash lights nothing absolutely no electrical power. So my neighbor comes over lifts the hood and I assume bumped something and all power is restored all the dash lights and dings I turn key back off and repeat no electrical power. So I get online do some research and find the issue with negative battery cable. And I had at some point experienced all the symptoms described. Radio turning on and off, stibilatrac light, service anti theft system. So I replaced battery cable and trickle charged the battery. But still zero power. I'm stumped unless I possibly don't have it grounded good enough. Please help.