you shorted a pin on the Mechanics Controller (the square chip with 144 pins, which points A,B,C,D,E,F,G,H and I go to) with the GND and that did activate the test mode.
You should clean it carefully and it should be back to a working state. Don't insist with putting discs while it's not working properly to avoid frying the laser diodes or focus coils(in the 400B laser unit).
SCPH-10000_GH-001 SCPH-15000_GH-003 SCPH-18000_GH-008 SCPH-30001_GH-005 SCPH-30000_GH-016(V4) SCPH-30001_GH-010(V4)
2xSCPH-10190, 2xSCPH-10350, 2xSCPH-10280
"**** j0 hackers!"
-Sjeep (As seen on TOXIC OS ELF...)