If the screws are not recessed, and you have replacement screws available, I recommend you buy a Dremel, and with the cut-off wheel attached, carefully cut a flat slice into the top of the screw so you can remove it with a flat-blade screwdriver.
Just hold onto the Dremel for dear life so it doesn't walk off the screw and cut your unit top.
Steve
Just hold onto the Dremel for dear life so it doesn't walk off the screw and cut your unit top.
Steve