Code 10 locked

[Rosco59]

Hi I’ve got a old 3 digit code sound 2000 that is displaying the number 10 now. The problem is that it has only got numbers 1-4 so can’t hold number 6. Any help would be great. Thanks

[redrooster]

Remove from car and connect it up to a battery charger. Then try leaving it switched on ...overnight without interruption to see if it resets