lately i've been driving manually with the 1, 2, d3, d4 gears (automatic transmission)

when i downshifted i didn't press the release button on the gear selector because it just moves so i didn't think i had to. but then then check engine light came up after a few minutes of driving like that and then i saw in the manual you're supposed to press the release button.

does this mess up the engine? what does it mess up? how much does it cost to fix?