Why the LOGO! is defective, I can not say.
I can not provide remote diagnoses and have no glass ball ....

If I put my old 0BA5 under voltage, then the background lighting of the display turns on, in the display appears an hourglass as the symbol for the run up.
After a few seconds, the hourglass disappears from the display and the date display appears flashing to prompt you to set the date and time.
A few seconds later, the backlight goes out, the flashing prompt for entering the date and time remains until the setting is made.