Horizontal Green line

Crack in display connector or other LCD damage would be indicated.

There is no fix for physical damage.

• You can try to run the Self-test feature check on the monitor and see if the horizontal lines appear during the test.

• You may also try to perform a factory reset on the monitor. Please refer to this link: https://downloads.dell.com/manuals/all-products/esuprt_electronics/esuprt_display/dell-12407wfp-hc_user%27s%20guide_en-us.pdf
•  . In this link, go to the 'Display settings" column and select 'Display Reset'.

no PC told no screen told why? but one line , does smack of LCD failure actual how to wave it ? (wave = cure")

AIO PC

or is this a monitor by it self.

we can not guess PC,  ok/

but there is a CURE,  A NEW LDC PANEL. 

IS THIS IN WARRANTY OR OUT. Also not disclosed that.