Managed to replace/ change Porsche 2M25J CPU on BCM, with back-up of original D-FLSH and P-FLSH in Xhorse VVDI Prog programmer.
I first tried it myself.
Rewrite partition for 2M25J
If the D-FLSH is 16K，set EEE partition as 8
If the D-FLSH is 32K，set EEE partition as 0
Partition division complete. Then write the backup D-FLSH, and then P-FLSH
Finish encryption in the end. Porsche encryption byte: 7D
However, the BCM cannot work at all. Failed to read data and decrypt.
Discussed with the engineer, i adopted the method below:
Step 1 – completely clear the encryption
Select the device and clear the encryption fully
Then CPU is all cleared. Again divide CPU partition. set the partition as 8
Step 2 – Write D-FLSH
Some data to modify before writing D-FLSH
Find out Line “7FF00” and replace “7D” with “FF”, then write CPU
Then perform encryption
When all above is complete, decryption and encryption-reading work ok.
So, a good device needs a good way to perform it for the best benefit.
Hope this helps.