power cord directionality


IF power cords do indeed have preferred directionality, and one is inadvertently flipped for a few hours, does it "harm"it?
128x128jw944ts
....thx for the straight answer!  Part two, should I have it fixed, as who trust knows if it was labeled wrong, is truly backwards, and if I send it back, how will I know what was really done?  Facepalm.....

Well, you would know if it was really done if the arrow is now pointing in the correct direction.
Why not call the manufacturer, explain your situation and see what he advises.
uhhh...  duh end wif duh prongs on it gits plugt innuh wol.  duh uther end innuh yer lektronix.  

how yu gonna ree vurs it?