Received your package. After checking, it turns out that the shift registers (all three — one on OSPi and two on expansion board) are all damaged. This is quite rare because the shift registers are usually very robust. I can’t think of a good reason, the fact that all three are damaged probably implies some sort of over-voltage situation. It’s also rare that the shift registers are damaged but the other components are fine (fuse, triac). When there is a shorted solenoid, the fuse may break, or triac may be damaged, but I’ve never seen shift registers damaged, particularly with no other components damaged.
My only suggestion is that when plugging in the expansion board, make sure to power off everything before connecting the expansion board. ‘Hot’ plugging in can be a potential issue. Anyways, I’ve replaced the shift registers and made sure both have passed functional test. It will be shipped back to you tomorrow. Thanks.