Hook the laptop up to an external display and see what happens. If the issue does not persist on the external, the LCD has a TAB failure and you will need to replace the screen.
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However, if the display is bad it isn’t cheap. Expect to pay around [https://www.ebay.com/sch/i.html?_from=R40&_trksid=p2334524.m570.l1313&_nkw=ASUS+Q405U+LCD&_sacat=0&LH_TitleDesc=0&_odkw=TL-SG1024DE&_osacat=0&_sop=15|~$144-158+, depending on who is selling it]. The panel is fused to the glass with UV LOCA glue, so you need to replace the touchscreen assembly as a unit — it can’t be done piecemeal on these.
Hook the laptop up to an external display and see what happens. If the issue does not persist on the external, the LCD has a TAB failure and you will need to replace the screen.