I have a 2007 accord. After 40 minutes, only bottom 2 lines of rear defroster are working. I replaced the relay, with fingers crossed and no luck. Any suggestions? Thank you

After 20 minutes. Another 20 minutes and no nothing

 

Sorry to say, the relay will not help, typically when only a portion of the defroster is working the grid has been damaged (often by jamming stuff on the back shelf and nicking the thin strands of the grid). As a general rule, the only way to fix it is to have the rear window replaced.

 

Sometimes a repair can be made with stuff like electrically conductive paint that's sold for this purpose. It doesn't always work, and it isn't nearly as durable as the original lines (in the event of getting scratched again).