Pls try to solve this problem as following steps :

Open '' menu'' ,click set up button – select service searching – select manual scan – select Inv ,then see if it can be locked ,if yes ,you can search the channel .

If this still not resolve this problem ,

You can do as follow:

you have to download the software from your old dm500c and then update it to the new dm500c that will work well.

Please find attach two update tools. dreamup is for Rs232 cable and flashwizard is for network cable connecting form dm500c and computer.

If you have a RS232 cable , please run dreamup as follow:

1, connect your old dm500c (power is off) to computer with RS232 cable .

2,act the dreamup and manu will display.

3,select port as com1 or com2.

4,click "connect" button .

5,connect dm500c power on.

6,click "backup" button

7,enter a file name and select a place in you computer.

8, wait … and click "complete" buttonr.

9,the software has been downloaded

10,disconnect the old dm500c and connect new dm500c (power is off).

11, act the dreamup and manu will display.

12, select port as com1 or com2.

13, click "connect" button .

14, connect dreambox 500c power on.

15,click "flash" button

16,select the software that has been downloaded from old dreambox 500c.

17,wait…until display the manu " flash update finished "

http://www.dreambox-500c.co.uk/

18,click "ok" button .

The program is show in page140-150 of manual .

If you have network cable please run flashwizard.