[B1257]

Then read fullflash and you have FF FF FF FF FF FF still.
On Bosch ecu it works all the time, not recommended for Siemens.

If you would have this szenario the checksum is faulty too.
When you working with flash it is important that you have the right programming and ersase supply current also data bus timing is very important. Most of the time I modify ECUs on the bench.

There is a third software called Minimon, but you need the right driver for the corresponding Siemens ECU and at least the right flash pinning which depends on the ECU board design.

I the past I was doing both ways, resoldering and than programming the whole flash in a SOP44 Adapter (Batego II), than with Minimon and JMGarge flasher. The results were always the same, even the checksums were correct. Therefore I build a MS43 ECU with a soldered boot tact switch and a SSOP44 socket for quick tests and replacement of the flash chip itself.