I'm experiencing issues with the LCD display on my Inspirion 15R 5521.

During POST I receive 8 beeps and the laptop does not boot up.

I held the D key along with the power button and the display illuminates with various colors but does not boot up.

I connected the laptop to a tv monitor via a HDMI cable.  While holding the F3 key along with the power button I'm able to boot up the laptop. By using the Fn key and F1 key I was able to get the display onto my tv. Everything appears fine on the tv display.  The laptop functions fine and no issues detected through Dell diagnostics.

Before purchasing a replacement LCD, are the 8 beeps a definitive diagnosis that the LCD screen must be replaced even though I have the following:

• Illuminates with various colors when using the D key plus power button.
• Shows a very dim white backlight when running.  Once boot up, if I use the Fn and F1 to switch 100% to tv I can see the LCD screen go 100% black.  If I switch back to split I can see the backlight again.
• The touch screen still works.

Any guidance would be appreciated.  I'd prefer not to buy replacement parts unless I'm certain of the root cause.