This worked for me.
After turning the the Galaxy 2s while charging, it would turn itself on within two seconds and the device would charge slowly.
Following a suggestion on one forum, I checked the cord plug at the phone end and removed a speck of whatever. It made no difference.
Then I checked the other end of the cord where it plugs into the mini-ac transformer and saw that it was not inserted all the way in.
I pushed it in all the way and that solved the problem.