just tried to up date iphone 3gs 16gb to ios 6.1.3 from 5.1.1 now the iphone is just sitting with apple logo and wont do anything???

put iphone 3gs 16gb on vodaphone network to update ios to 6.1.3 from 5.1.1 left phone plugged into power and left it to do update on checking iphone

it is now constantly rebooting every 2 -3 mins. how do i get out of this. its not now being recognized by itunes. cant find its box and cant get into phone for

imei number etc as phone is not going past the apple????

anyone had this problem as i have no idea how to get out of this reboot cycle.