It would be good if you could plug into a GFI protected outlet to test these controllers, it would trip much more quickly and there would be less damage.
Here is what I would do: Get another unit ready with tested semiconductors. Before you mount the SCRs to the panel, measure the resistance with an ohmmeter across 1 and 4 of the terminal block. Then measure again after you mount them to the panel. If you get a different (lower) reading DON'T plug it in.
The SCRs will need insulating hardware, or you will need to replace with iso-tab types. (easier)
Mark