XBOX360 Controller Will not connect. Only two flashing light cycles.

I have a XBOX360 Elite and works fine with one controller.

The second controller now does not work. About 1 year old

I get two flashing lights when I press start, then they stop.

I exchanged the battery pack with the good one I new worked. No change.

Opened , found some sticky residule and cleaned the board with 91% Alcohol and blew dry, then used heat gun. No Change

Based on this, the console is working with the other controller. Battery does not appear to be the problem.

I would greatly appreciate your expertise in helping me resolve the connection issue.