Issue
Last night I had an issue with my Sony Ericsson W910i, where it could not be closed after it was opened. It would slide a few milimeters, but that was it.
It appears that both of the screws in behind the battery had come loose, and one of them had wound itself right out of it's threaded hole.
Solution
- Turn the phone off.
- Turn over and remove battery cover.
- Remove battery.
- Check tightness of the two screws, see attached image for location.
- To tighten the screws you will need:
- Either a very small Torx driver; smaller than T8, possibly a T6 or T4.
- Or a very small flat bladed jewellers screwdriver may do it.
- Check mechanism slides smothly.
- Replace battery.
- Replace cover.
- Turn on phone.
Image
The two arrows in the phone's battery compartment show the location of the two screws.
The arrow on the batter lid shows what the screws looks like.

Summary
I had a quick google for this issue and couldn't find a resolution listed anywhere, so I hope this helps someone in the future.