Samsung fridge is accumulating ice on the evaporator coil

Samsung fridge is accumulating ice on the evaporator coil and tested all sensors,thermostat and the heater element using multimeter on continuity and they are producing a sound indicating circuit is complete

Started after everyday electricity loadsheading and when power is back the temperature control panel only show 1 middle light and has to reset for 3 or 5 lights to appear

How can i solve this problem please