What the others said; recharge and test. That said, your unit probably has a "dual purpose" battery from the dealer. I was a battery distributor for a long, long, long long time and such a battery is nothing but a specially labeled starting/cranking battery that can be sold cheaper than a true deep cycle. Even if such a battery is OK, it will typically deliver only 20-25 amp hours. Think, leaving your headlights on in your car, and how long the battery will deliver power.
Look into replacing it with a real deep cycle, which will be rated in amp/hours (Ah), NOT CCA (Cold Cranking Amps), MCA (Marine Cranking Amps). Trojan deep cycles are highly rated, but Sams Club sells decent deep cycles. If you have room, golf cart batteries are a good idea. Our unit was short on space for 2 6 volts so I installed a GC12 (12 volt) cart battery.