To test the cash drawer you can select the option of ‘open drawer’ or by processing a transaction which would also normally open the drawer on the processing of the transaction.
If you are unable to open the cash drawer on your EPOS till, firstly, check if the cash drawer is locked via the manual key lock! If not, check there are no loose cables going from your cash drawer to the till.
Some cash draws are not plugged directly into the till, instead they are plugged into the printer, which is, in turn, plugged into the till, check all cables between the till -> printer -> cash drawer. If your EPOS is configured in this way, try to print a receipt, if the does not print then the issue could be with the printer or the connection between the till and the printer.