a question !
some friends have completely lost the serial
what should they do to find the serial!
The serial number is not lost. That device is bricked and you (or your friends) must unbrick it.
The first step is to put the device in boot mode, like this:
If you have a steady hand, there's no need to solder that resistor; just keep the resistor terminals still in the indicated points while inserting the usb cable. The programmer should enter in boot mode and after that remove that resistor.
Once the device is in bootloader mode, flash the firmware dumper by selecting "firmware dumper" and click reflash.
If the firmware dumper reflash was sucessful open the Advanced window. It should look like what you posted in a1 image.
Make sure to check the "code protection bit" checkbox and click the write button next to it.
After that in the "device serial code" field click the write button to correct the wrong checksum.
That's all! Close the advanced window select "TL866A firmware" in the main window and click reflash.
You should now have a working device!