Motorola HTX checksum update

[Telekom]

I have tryed to convert an Akeri HTX to an CP1000 HTX:
How do i update the checksum after a rebuilt of the coduplug on a Motorola HTX (EEPROM, Flash EPROM). When I have written the hex files to flash EPROM in bank 0 and bank 1 I get "Checksum disabled!" and "Hardware revision number= 00".
And when i try to write to the radio with fieldprogrammer i get:
"Checksum error"
"3 sectors must be erased, Erasing sector number 1"

I start service mode with F4 in main->
When i try to update checksum I get: "Service mode not started".



Thanks