Why did my diodes die?

So I was building a laser for a customer, using a m140 diode and a DIY mohgasm linear round driver in a C2 host. But when I finished and tested the laser, the output was way too low, and when unfocused the laser output was a bunch of lines instead of an uniform circle.

I thought there were something wrong with my driver, maybe a short somewhere, but when I disassembled the laser and probed it with my multimeter, looking for a fault, I found nothing. The driver seemed perfectly normal, and the it outputted the correct current. So I thought maybe the diode was DOA, and I wired up another diode to the driver. But the same thing happened again. And hen I turned the laser on and off again the output had decreased even more, it was clear that the driver was frying the diodes.
I finally changed the diode and this time also the driver and now it was working.

While I'm pretty pissed about losing $120 in a flash, the most annoying thing is that I have no way of learning from my mistake because I still have no idea what I did wrong, the driver acts like any other driver, and I am certain it was not static electricity from my fingers or anything that killed both diodes.. So what I'm asking is: Do any of you have an idea about what could be wrong with my build? How can I properly troubleshoot a mohgasm linear driver?

So far everything points to the faulty driver...

I guess it's a bit of a stretch to assume you have an osciloscope to check out the output?

Sounds like a big spike at startup, followed by the normal current output you'd expect. What's it output capacitor looks like, possibly b0rked?

It's relatively common for something to short to the case when you assemble it. I've had this happen a few times with flashlights. Nothing works when assembled. Take it apart, and it starts working again.

Its possible the regulator is damaged. If you want to send it to me I can scope it and see whats up.

The same happened to me too

sounds like a real pain. id go with cyparagon's advice

Does your multimeter have a min/max readout?

I'm sure you've tried this if you had the feature but perhaps you can see if there is a brief spike when the driver is powered?

This is all great advice. I'm betting the problem is very small.