btw those clip leads are usually garbage.
wire too thin and it is simply folded back and crimped to the clip.
they are often bad right out of the package.
as you found out unreliable tools=wild goose chase.
as for the original driver unless it is blown up the only thing i see fail are the input and output caps.
seen plenty of those cheap switches go bad.
they dont stand up to inrush current.
the input cap gives plenty of that if it is good.
A little late but here’s the update.
Despite ordering from within europe it took a while for the new switch to be delivered.
And when I got it I didn’t find the time to work on it again.
But I have installed the new switch and did 2 rundowns and everything looks to work as it should!
I’m going to deliver the light on monday and see what my friend thinks of it.
If he thinks it works and is as bright as always, now we know they mislead him.
In the end a lot of work for what looks like a defective switch, but at least I’ve learned a lot!
Thanks to everybody that contributed to help! Very much appreciated!