It's common for the DME solder points to go bad, I've had DME's rebuilt by
ECU Doctors very competent and quick.
As to the immobilizer, If the immobilizer is bad, which is possible, ECU Doctors also does them
You can by pass it but to do so 2 things need to be done
1)the chip in the DME needs to be replaced w/ a chip that does not expect an immobilizer signal.
2) the R61 relay needs to be by passsed, see
this thread