Side effects of too much potassium?

to ways to overdose on potassium - too much or too little - my grandmother was placed in an old folks home and within 48 hours they misread her potassium level as too high and it was too low and the idiot gave her idk which ended her life - my grandmother knew it would happen, she told me 4 days prior - in another hospital, but without auxiliary insurance she was transported to a long-term UNSKILLED facility and within 48 hours - she was gone - the question for me was the idk and the nurse who did it - one should never be answered - i loved my grandmother.