stupid question re mobile phone - please help

[motherpeculiar]

my mobile phone is displaying a message
"usb data cable has been removed"

out of the blue - I've never had (to my knowledge at least) a USB data anything on this phone

it just started yesterday and is coming up all the time now (driving me mad with its beeping)

don't know model number but it is a nokia, relatively recent

also I can't get the back off it, thought if I did this and reseated battery it might be ok, but I can't open it. This was actually my original "stupid question" - how do I get the back off?

(everything is going wrong today and I am close to meltdown so any help would be most gratefully received)

which model?
I have trouble getting the back off mine - nokia also. a button needs to be depressed near the base on the back and the back cover slid up but it's very twiddly and hard to do. I use a paperclip as a lever - insert it between the top of the button and the phone cover and lever up. HTH.

The pins on the base of your phone may be damaged slightly and giving the phone the impression that a cable has been taken out -try blowing dust out, or actually inserting a cabe then removing it? ( you should have received one as part of the phone pack.)

thanks eefs - I managed to get the back off following your advice with the paper clip - so now I know it is model 6230

didn't help with the usb cable message though - will try your other idea, if I can find the box that the phone came in

(really don't neeed this today, we are supposed to be going on holiday tomorrow morning but have lost booking reference as DH's laptop died and we stupidly hadn't printed it out so am trying to find out who we are travelling with and when in the middle of a full day of work - aaaarrrrgh)

thanks again