Too new for someone to have to do a refurb on already and manufacturers are very unlikely to share that info with the general public. So probably next to nothing available for what's under the deck beyond more than likely foam flotation.
If you are the original owner, there is a warranty. You might want to get the process underway on that with the marina and Chap.
There were (2) different 19 H20's that year - the Fish & Ski version (which has the livewell, trolling motor, etc) and what I will term the regular version which omitted all the fishing amenities. Which do you have? Motor?
On my Fish & Ski, the livewell is dead center under the rear seat, right in front of the engine access hatch. It's 2 batteries, one each side of the engine. Gas tank is dead center in front of the 4.3L v6.