There are a few phantom draws on the battery. For me it takes about two weeks for me to notice the battery level dropping. You might able to bring the battery backup. It might have been damaged slightly or majorly. For sure you have shortened the life. Give it a try, it will take an all-day charge using the on board charger to know if it will hold a charge. Once off the charger let it site for an hour our two to stabilize and use a volt meter. A strong battery should be able to hold a 12.66V charge. Good car repair shops can do a hydrometer test on each cell can tell you for sure what the health is. My local auto shop did it on my old trolling motor battery for no charge.
When we leave the HTT for any amount of time I disconnect the battery. Just make sure things like the electric tongue jack is also disconnected too. A battery disconnect switch is handy as you do not have to open the battery cover everytime.