Before I learned to flash roms for my self I used a service I found on E bay in my country, Britain, just search for
Android Rooting & Custom Software Installation, cost is about £10 plus postage. https://www.ebay.co.uk/itm/Android-Rooting-Custom-Software-Installation/283551967309?hash=item420503a84d:g:VoYAAOSwGvhUHGfw