how can I fix my tomtom 700?

My tomtom go 700 was working fine, I switched it off and put it in a draw for a month and when I got it back out again it didn't work. I placed it on charge for a while and switched it on, the green power light came on but nothing appeared on the screen and I could no longer switch off the unit and had to wait for the battery to die, tried reseting no joy there, any help gratefully recieved.