Korg DW-8000 no LED

Have owned my Korg DW-8000 since I bought in 1986.
Everything worked fine until I changed the battery.
Now when I turn on, some of the LEDs flash, I hear the expected jarbled white noise. Was planning on reloading sounds from the original cassette.
I cleared the ram (5 & 8), which cleared the noise.
Tried loading sounds “blind” with no luck
Also reseated the main board and reconnected all the connectors
Any trick to bringing the LEDs back?
Can’t seem to load anything without a display

Loading the sounds back is only one possibility to put proper sounds into the memory. You may edit a sound with resonable settings (blind of course) and store this sound then to the other locations. Assumingly any valid setting is “reasonable”. So it should be enough if you select a parameter, put the slider once fully up and down, and go to the next parameter, and on and on. Finally store this sound.
Perhaps it is even enough if you store only the sound 1-1. But to be sure, I’d store it no all 88 locations.