2009 toyota matrix has not been driven regularly since 2019 when it got a new battery. Since then we have removed the battery and stored it indoors (not on a trickle charger) for winter then in the summer installed it in the car which we will drive 5-10km a month in to spin up the alternator. In May I installed a new radio in it as I was planning on insuring the car and driving it which did not end up happening. Now the battery will lose charge within week or 2. My dad thinks it is the new radio since the battery has little to no use. I tried to explain that since it was not on a trickle charger and it is not a deep cycle battery that we likely killed it by letting it sit to over 2 winters. Any thoughts? I am insuring the car in a week for work and don't want to get stuck:)
Car Radio for reference: https://www.amazon.ca/dp/B07Z4KY6X1/ref=emc_b_5_t