I had a go at removing the case back today but no joy

I followed the instructions given in the link, removed the band, shaped a small screw driver to fit into the groove and tried a twisting action but it didn't budge, are the case back normally difficult to remove? How do I proceed?
If I do manage to get the case back off will the module come out in one piece like a LED module or will I get a jigsaw of parts?
Is the crystal glass or plastic, I thought it was plastic but the instruction state glass?
I would like to see this watch up and running and if this can be achieved I intend to keep it for myself, my initial ambitions was to dismantle the watch, clean the contacts and the buttons to hopefully get it working again and whilst it was apart polish the scratches out of the crystal and clean it up a little.
I do not want to risk doing any damage to the watch, my failed attempts to remove the case back has knocked my confidence in trying anything myself, if someone can point me in the right direction I might give it one more go but failing that who would be the best person to send it to for repair?
Any help will be gratefully received.
