I have one of these scanners on my desk and simply pressing SCAN takes the scanner out of any type of search back into scan mode.
Strange... Maybe try having them press MAN and then SCAN to see what happens.
It is possible the SCAN button has stopped working.
These scanners are notorious for the contact material flaking/falling off the back of the button that makes contact with the circuit board. An E-bay seller sells some "keypad fix" glue (metal/rubber mixture) if this is the problem and someone knows how to open and get to the button.
A NON-TOXIC GREEN ALTERNATIVE TO THROWING OUT WORN OUT KEYPADS. - Garage Door Opener Keypads. - Parking Access Keypads. Dries tack-free in 2 hours. EACH JAR OF KEYPAD FIX CONTAINS 0.3 OZ 9.0 ML.
www.ebay.com
Another person mentioned once they just glued a small piece of aluminum foil onto the back of the button.
Shawn