MacBook Pro (13-inch, Mid 2010) won't go to sleep, nor will it wake up from sleep
Solution 1:
Try to reset the SMC as well as the PRAM.
Solution 2:
This exact same situation was happening to me and the weird part is that the machine will sleep initially...say 2 blinks of the sleep light, but then will wake back up !!!
Looking at the Activity Monitor is a process called "Android File Transfer". I decided to kill this process and now my Mac is sleeping.
I am going to monitor moving forward, but this appears to be the culprit!