You might want to ask the dealer you carried your vehicle to if they used an "on-car brake lathe".. If so, your sensors might have metal shavings all over them (because they are magnetic)
causing this ABS light of yours. If they don't use an on car lathe, then I would suggest having it scanned. Or try the likely source, the rear speed sensor on the top of the rear end housing.
Good Luck in solving your ABS light