ok so i have an auto audi a4 1.8t quattro it will not start no cranking no lights nothing but thats when the positive is on the terminal on battery (how its suppose to be) but if i rest (meaning its not connected just set on the terminal) the positive connector on the terminal lights turn on and im able to start it what could this be its been sitting too long help me please also when i do get it started from the connector resting on the terminal there are no check lights just the abs i believe thats what it is called.. so frustrating if u dont understand what im talking about just lemme know ill try and explain better but any help will be appreciated thanks

 

clean the cable terminal connector.. maybe theres corrosion on the connector.

 

that was the first thing i did when it started doing that its clean enough to eat off of lol does anyone know what else it could be PLEASE HELP