In order to see the brake release mechanism, you will either need to tilt the washer back and take the bottom panel off or use a mirror. When you rotate the pulley, the cam dog should rotate towards the brake hub dog and a gap should open up between the cam hub and brake hub. If this is happening, then the brake release is probably ok and if you rotate the pulley hard and fast and the metallic clanking sound you hear is the two dogs hitting each other, then the brake release is again, probably ok. This means something is jamming the inner tub from turning. Could be clothing between the tubs, a seized tub bearing, a worn split ring (drive block) or the inner tub hub is bad. A worn split ring or bad tub hub can causes the inner tub to rub against the outer tub preventing it from rotating. You will need to remove the agitator and inner tub to figure out the problem.
BTW, make sure the transmission pulley nut is tight. A loose nut can prevent the brake release from working.
Source: How can I bypass door sensor on GE washer WLSE3150A0WW