On my Sharp AlL 1631 copier there is replace drum

On my Sharp AlL 1631 copier there is a replace drum light that will not go off. The unit will not work until I can get this light to go off. I have replaced the drum with a new one that I tried in another unit and it is good.I have replace the toner cartridge and the copier lid assembly. I have cleaned everything in the copier and the drum light will not go out. At power up the unit acts like it is going to work but then the drum light will come on solid and nothing will work. Can someone please help me with this issue? My email is lhoward@todayscomputers.us