Cant Pair controller, flashing light only

my controller keeps flashing green. i press pair buttons on pc Xbox 360 and controller, and they can't pair. i changed batteries so power isn't the issue. i don't know how to fix.

crwdns2934089:0crwdne2934089:0 crwdns2934093:0crwdne2934093:0

crwdns2934109:0crwdne2934109:0

crwdns2889612:0crwdne2889612:0 0
crwdns2934285:0crwdne2934285:0