My diagnostic card is an SD-15A which matches my manual.
Did the instructions change for SD-15B or S-15C? I don't know. The instructions for the SD-15A are simple:
1. Load sides 1 and 2.
2. Press A.
3. The calculator should pause displaying -7.777777770 -77
If it doesn't there is a malfunction in the card reader, program storage, program control, digit entry, the registers of the operational stack, the x<>y function, the Roll up function, the pause command or the display.
4. After the one second pause the calculator should run for about 50 seconds and pause to display the following values in order:
1. 07
10.000 06
1.0000 07
1.0000000.00
If the calculator stops before displaying these values the number in the display indicates one of 53 error codes.
If you suspect that you somehow have bad cards let me know and I will send one to you.