Yesterday I checked around temerature control of PROMETHEUS for ALS Y, and found that the core and the outer ground of the BNC port for temerature control are short-circuited with each other. Multimeter showed something like 1 Ohm
Mamma mia! Now I am sure It's broken.

Note:
- The BNC port is located on rear side of the controller of the laser.
- To check if the short of the BNC port for the temp. control really means the controller is broken, I checked the same for PROMETHEUS for ALS X, which is properly working. For the X laser, the impedance between the core and the outer of the BNC was measured to be ~ 105 kOhm, which is comparable to the number the manual says is nominal (100 kOhm). 
- Izumi-san has already made a contact with the company we bought it from.