Hi,
I tried all different option and nothing helped. Then I just tired the regular steps to clear RAM as if the calculator is working good with the batteries all installed.
I turned on (The screen was blank, but I pretended that it is working), then
# Pressed 2nd MEM (that is the second function of the + key)
# Selected 2.
# Selected 1 (All)
# Pressed Enter
In few seconds I turned it on and then adjusted the contrast (2nd, up or down navigation buttons multiple times) to see the regular home screen.
Hope this helps!