There is definitely some corrosion from the batteries but I have seen far worse. How is the other end of the battery compartment?
If the test fire button on the back of the flash works, then the batteries/battery contacts are NOT the issue.
Rodger
EOS 1DX M3, 1DX M2, 1DX, 5DS R, M6 Mark II, 1D M2, EOS 650 (film), many lenses, XF400 video
