Now it is saying e3?

Hi.
E3 just means illegal operation. this means you have pressed the wrong buttons. If it happened as soon as you pressed the clerk button, then you either have the wrong clerk code, or the clerk button has been removed from that position. Do you know who programmed this machine? Maybe you could find out the logon code from them. Otherwise, it will be tricky without a programming manual.
If you are able to obtain one, I can help you further. Failing that, I may be able to find some info if your model is similar to others that I have serviced. Are you able to take a photo of the keyboard and send it?

Mark
September 2008