To Bph&co,
Yes you are right about CRC, but mind you
that I was trying to make things very simple.
Anyway, the reason why all locks are closed
because the Checksums or the CRC in the
EEPROM does not match the Checksum and CRC
in the Cobba, MCU, etc. The phone is not
actually locked, but totally disabled and
no unlocker can unlock it. It is useless to
copy other phone's eeprom even with same
version. Changing the imei on the other
EEPROM to match the original EEPROM will
still not solve your problem. The EEPROM
is heavily secured and a single byte that
is not correct will automaticaly disable
the phone, especially if this byte is part
of the IMEI or the lock infos.
You can however remove the locks via EEPROM
modification with correct checksums alone
and not CRC because the lock info is only stored in the EEPROM (I dont know if this is
true for newer versions). But even if your
phone is unlocked, it will still not connect
to any network because of mismatching CRC in
different chips. So it is still useless...
EEPROM rebuilding can be done, however you
still need a TDF-4 Box to flash the phone
again to calcutlate for the right CRCs and
checksums.
Using another phone as a experiment unit will
still not solve your calculation problems
since every phone uses a different "key byte"
to calculte for the proper hex information.
Same software version may mean same algorithm
but still the "key byte" is different so
still useless
Practically, it is very hard to restore IMEI.
When I had this problem, I destroyed the
24C16 by heating the IC. Then I assembled
the 5110 again. Turn it on and saw "Contact
Serivce". While the phone was still on, I
dropped it inside a glass filled with water.
Now phone is totally destroyed! The next
morning I went to nokia service center to
have it fixed ;p They tried to dry the PCB
and realized that EEPROM was burned. They
think that the water caused the EEPROM to
be short circuited and thus burning. Heheheh,
they replaced the PCB and fixed the phone
that I destroyed for me
Do not try to ask the service center to fix
your phone normally. They will know that you
tried to play with the EEPROM and thus they
will not fix it even if you pay them
Best Regards,
Linuz