Update and Fix Current M2 site

I have an existing site build on m2.2.3. I would like it upgrade on latest version. Keeping all functionalities and design. The website should be 100% responsive on all devices. I also have another url where site is already upgraded at m2.3.0. Theme is also upgraded and modules are also upgraded. However need to double check all is well if continue from there. The issue on m2.3.0 i see is if i inspect in browser and check the console there are too many errors in console. maybe this is because some files are missing or need to run deploy that's why i want to make sure things are ok before proceed. I only need experienced person who has experience is both frontend and backend and can do work fast. I need this done fast. No delays will be accepted and project will be cancelled upon delays or no response. More details are attached. Url will be provided to interested bidders and discuss on PM Website will be shown in PM and more details will be discussed.