Update: Laser PSU confirmed dead. Here are some photos of the burn marks.
Last time the laser tube failed, we installed a spare tube and it still didn’t work, so we suspected the PSU and replaced that. When it still didn’t work we realized our spare tube had failed too. It’s a long story, you can read about it here. In any case we ended up with an extra PSU which was kept as a spare. So this morning @Katie and I swapped in the spare. This involved carefully splicing the HV wires. We cleaned up some of the other wiring at the same time.
The laser is working again, but it is not yet online for general use. There is a configuration issue in LaserCAD which may have been a contributing factor in burning up the PSU yesterday. Until we can solve that, the laser is out of order.