Even if you got the FPGA from AliExpress and soldered it in, I would assume it would not work.
This is because, of course, it does not contain firmware, and most update tools can only be written in a normally operating environment.
Even in that case, we usually do not write all areas of the firmware, but only the areas that have been changed.
Besides, what about calibration data, etc.? Of course, it is not in the new FPGA, and in most cases, it is not written by the update tool, etc. Of course, the adjustments are different for each model.
Therefore, it is impossible to repair unless the FPGA firmware is extracted from a working donor.
Suppose you extracted the firmware from the donor and were able to repair it, but it would not be very usable. The dead pixels, temperature adjustments, etc. are naturally different from one thing to another.
So we would have to recalibrate it, Can I ask Fluke to recalibrate? I don't think so.
You will be lucky if you can extract the firmware from the dead FPGA that is now installed.
We can't help you with no pictures either.