How can we fix it.. Their is a P5 00 in the screen we cant open it?

Manual here: http://www.cashregisterhelp.com/files/M-ER5100-5140_V2.pdf

You may get more mileage in a dedicated user forum for your machine. A Google search may be useful.

Also: Learn the difference between "Their", "There" and "They're"

try:

Idiots, THEY'RE looking for THEIR ball in the wrong place. It is over THERE"

XXX
February 2017