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Most scripts check that the screen being shown is the one expected. That's why at the end of most scripts there is a line like this one:
/* Check for arrival at <form name> */
if ( !(CHECK_CURRENT_FORM("<form name>","Unable to display form <form name>")) ) return;
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You should be able to manually reach the unexpected screen because you know what to do, what to type and what keys to press in each screen.