As indicated by others, magnets will not affect LED or LCD (or plasma) screens

Can a magnet ruin a LED TV?

The good news is that magnets won’t damage LCDs. Even when placed in close proximity to an LCD, a magnet won’t affect its color or other display elements. Many LCDs feature built-in speakers, for example. These speakers often contain magnets, which won’t harm or otherwise affect the LCD’s display.

Are magnets bad for screens?

But LCD and LED monitors (the flat screen monitors we use today) function completely differently, so they are generally not affected by magnets. After all, your speakers use magnets to work and they don’t mess with your monitor, so the MOS is perfectly safe to use. … All you need is a magnet and a CRT.