redirect wordpress dashboard

Hi Guys ,

I wanted to redirect my old domain to new domain
i saw this video on youtube
https://youtu.be/FlNov7ZFX70

and when i went wordpress setting > general > changed the old url to new

I can’t access to the new and when i try to open my old dashboard it redirect to the new please help

old : http://www.goprohero.ie
new : http://www.mycamera.ie