[Q] Nexus 5 wont turn on topic

Im sorry if someone has already posted this but I need help.

I rooted my N5 using a simple guide of drag and drop so i could use appradio.
I followed a video on youtube to remove the bar at the bottom of the screen which worked by adding something to the end of the build.prop.
After doing it- it worked but i thought i would be able to bring it back by deleting that line of information on the build.prop. Now the phone will not turn on at all.

I can load into the bootloader but will not start recovery- just an android sign with a red triangle. Turning it on normally will only load up a black screen so i think it must be something to do with the OS?

I tryed following a guide to fix it to do with the fastboot mode but found that it didnt work as it was not as up to date.
Heres the details if it makes sense to some of you:
bootloader version is HHZ12d
basebamd version M8974A-2.0.50.2.22
variant hammerhead D821 (E) 16GB
HW version- rev_11

I am not very technically minded but any help would be much appreciated.

Thanks

Zack