You need to call Matt for service or questions. It should not have fully discharged in the resting state it was in after 6 months. He will take care of you.
From amped web page.
(LiFePO4) Batteries
Q – Do I need to use a lithium charger?
A – We HIGHLY encourage the use of a LiFePO4 charger with our batteries. Your SLA charger will put a charge on our battery but are typically only 13.5v vs LiFePO4 chargers being 14.4-14.6v. To ensure a full charge, speed of charge and proper cell balancing, it is wise to use a LiFePO4 charger. We sell these with batteries at or below cost to enhance our customer experience. Deltran and many other chargers that show will charge lithium, often do not include the feature to reset a BMS. This means they will not charge a battery that has been fully drained.
Q - Warranty and Money Back Guarantee of Amped Outdoors Batteries?
A - We offer 2-5 year warranties on all batteries. Our warranty will cover more than most gimmick warranties in the industry today claiming 10+years. See warranty section for details. We also offer a 30-day money back guarantee on all batteries from date of purchase. *
https://ampedoutdoors.com/pages/faqHow to Obtain Warranty Service
Contact service at ampedoutdoors dot com or call 715-914-7274. Most warranty claims end up being educational or charging related issues, which can easily be resolved through troubleshooting. If we deem your product is defective after troubleshooting first, then, you will be issued an RMA number and can move to step 2.