Right after fixing one of my SEs, my only BlueSCSI died. Don't know what happened, but when tested on both of my working macs the lights don't come on and it does nothing. Tried using the usb port to power it but also nothing. I think I broke it by plugging it into my SE while running. Is it fixable or should I buy a new one?
Putting the BlueSCSI to one side, do not hot plug connectors on vintage computers. Very few things were designed for hot plugging. Serial is the only thing you can hot plug on the back of an old Mac (if that), and hot swapping can blow chips on the board. Be patient and power down, switch the plugs, power up.
BlueSCSI wise? You're lucky it was the BlueSCSI and not the mac as they're much cheaper to replace. BlueSCSIs do that, they're not long lasting, especially if mistreated.
If you're able, I recommend replacing it with a ZuluSCSI. They are more expensive, but also a better, more resilient and long lasting, design.