has a similar Samsung... 2150 I think...
The page counter sets of the flashing light when it reaches a predetermined no of pages printed, (3000 I think, but don't quote me on that!).
When a "new" cartridge is inserted the printer detects a "new" fuse and the fuse "blows". This resets the counter, and stops the light flashing. If you put a catridge in that either doesn't have a fuse, or has a blown one, the reset doesn't happen.
(That's my understanding anyway!)
The fuse is a small one, located neat the front left of the cartridge, ... That is to say as you are inserting the cartridge it will be forward of you left hand.
That's all assuming that your's works the same way as my sister's!