Typing wifi password without using remote

Unfortunately, until it is connected to a network, the remote is the only way to control the Roku. To be honest, putting all sorts of weird characters in a password doesn't really help security all that much, and can cause problems. Try to use just standard text and basic punctuation symbols like exclamation marks and similar. Same with making it insanely long. There is a point of diminishing returns. Most hacking would come from a compromised device inside your network, not someone hacking into your WiFi.