Welcome to our forums!
Have you seen the TechnicsKeyboards site? I'm not sure how active it is anymore, but you could start there:
Technics Keyboards Website
technicskeyboards.com
I think there are a few members of the PSR Tutorial Forum who own, or have owned, a Technics keyboard, so you could also check there:
PSR Tutorial Forum – Your go-to community for Yamaha keyboard enthusiasts wordlwide. Share tips, tutorials, styles, voices, expansion packs and insights on Genos 2, PSR SX and Tyros models. Connect with experts, access resources, and enhance your music-making experience today!
www.psrtutorial.com
And of course you can also ask for help here! I don't know how many members here are familiar with Technics keyboards, but most keyboards share at least certain similarities as far as their functions, otherwise anyone who's familiar with one brand's keyboards and then buys a keyboard from another brand would be hopelessly lost. The way all of the controls and functions and menus are laid out will of course vary a good deal, but the basics of what the controls are for and what sorts of functions are available should be at least somewhat similar.