Stripped screwhead in mobile phone

[Consignia]

I'm trying to repair my old mobile phone after I dropped and broke the screen. I've got the replacement screen, but I'm trying to remove the assembly and in doing so I accidentally stripped a couple of the screws like this:

(Full Size image)

Anyone got any advice on how to remove them now? I'm not fussed about loosing the screws at this point, but I would like to at least get them out, so I can get further.

[El Unicornio, mang]

Putting an elastic band between the screwdriver and screw sometimes works.

There's a load of different methods listed here, but you might have to shell out for some kit

http://www.todayifoundout.com/index.php/2010/02/the-12-best-ways-to-remove-stripped-screws/