got an iPod 4th generation that won't unlock the screen

got an iPod 4th generation that won't unlock the screen
got an ipod mp102, showing that is fully charged but after the last sync will not respond any command and shows the screen locked (lock icon) i move the switch to the hold position and back but doesn't work, tried to do hard reset but since the screen is locked is not responding, any suggestions?

ANSWERS:

"gbowtransports, check to see that your switch still engage when moving the outside slider. This will not relate to the firmware update, and it could only have been a coincidence. Check this guide,

step 9 for a picture of the switch mated to the slider. If that does look okay, I would try to replace the small PCB that houses the switch as well as the headphone jack. Hope this helps, good luck"